The Mock Battle Arena is a training facility on the eighth floor of the dungeon where card-bearing crawlers can test their decks against simulated opponents. A visitor chooses a difficulty and an environment before combat begins. For Carl and Princess Donut, the arena provides their first controlled view of how captured totems behave after being summoned, how Donut's hand cycles during a fight, and how an opposing deckmaster can disable a deck before its strongest cards come into play. Its protections prevent generated enemies from harming the crawlers, but the entry warning expressly leaves environmental hazards and self-inflicted injuries possible.
The first trial
Carl and Donut enter the arena on December 12, while the floor's assault phase is still scheduled for December 24. Donut has only one of her eventual six totems and five cards in her deck. The interface warns that the deck is incomplete and that a consumable card will still be lost if used inside the arena. The initial choices cost 1,000 gold for an easy opponent, 2,000 for an opponent equal to their deck, and 5,000 for a challenge. Donut wants to try the challenge because winning it promises further options. Carl insists on an easy fight first: they have not yet established whether Geraldo, the monk seal they captured, will obey them.
They reach the arena through a door in a hallway that changes to fit their circumstances. Sister Ines's squad enters at the same time, but once the door closes Carl sees only Donut and Mongo with him. The starting chamber is a vast, bare space with concrete underfoot and metal walls. Donut then uses the environment controls to replace it with an outdoor colosseum filled with cheering Nebular spectators. Her adjustments alter the apparent gravity and replace flowers with grass and trees. She can also set the crowd's attitude toward them, although she cannot replace that crowd after choosing the setting. The scene demonstrates that a mock battle need not take place in the plain room through which its participants entered.
A countdown locks the deck ten seconds before combat. When the first hand appears, four enlarged cards hover before Donut and obstruct her view. Carl directs her to change their display size and position. Before she finishes, Mongo reaches the easy opponent and destroys it without a totem being summoned. The enemy disappears, the combat-complete notice resets the deck, and the arena offers another attempt. Carl regards the fee as wasted because the fight has taught them little about Geraldo or the cards. The episode also shows a limitation of an unrestricted trial: allies who can fight outside the card system may end it before the deckmaster practices using that system.
For the second easy trial, they put Mongo away and choose an abandoned version of the arena, without the distracting audience. Donut's opening hand lacks Geraldo despite his being in the small deck. Carl explains that having no totem available at the outset leaves a deckmaster vulnerable and tells her to discard the Combo card to draw toward the seal. Discarding it removes it from this battle's hand, rather than permanently destroying the card. An empty position displays a ten-second countdown before the next card appears. Donut then draws Geraldo. The trial turns an abstract deck-building concern into an immediate one: a hand can contain useful support cards and still fail to provide a creature that can defend its holder.
When Donut summons Geraldo, a sixty-second timer and health bar appear above him. He bears a miniature form of the team's flag and responds to their instructions, giving Carl and Donut their first chance to judge his behavior as a totem. Donut applies the Stout card, increasing his health, and a Time Extend card, adding sixty seconds to his remaining duration. A second Time Extend will not attach. The interface tells her that this uncommon totem can hold only two utility cards. Carl considers what that limit might mean for other rarities, but the trial itself establishes only Geraldo's two-card limit.
The opponent, a level-35 Squonk, proves too weak to test Geraldo in combat. Geraldo refuses to touch it, and it dissolves without being attacked. The deck resets again. Carl concludes that easy difficulty is poorly suited to measuring the strength of their developing deck. Across the two early runs, the arena has clarified the card display, draw delay, timed summons, utility-card limit, and practical need to manage non-card allies, yet neither enemy has provided the sustained fight he sought.
Preparing the full deck
Near the end of the floor's preparation period, Cascadia announces that arena prices will rise and that defeating the challenge level will unlock new options. Carl and Donut return after assembling six totems. The equal-deck fight that had cost 2,000 gold now costs 2,500. Donut again urges the challenge, but Carl wants to test their current deck at medium difficulty first. The price increase makes repeated trials expensive; they nevertheless spend hours in the facility because the approaching assault gives them little room to learn their cards in an actual fight.
Their test deck contains eighteen cards. Its six totems are Geraldo, Asojano, Skylar Spinach, Uzi Jesus, Raul, and Shi Maria. Carl and Donut have discussed whether that size gives them a good chance of drawing a totem in the first four cards while leaving space for other abilities. Carl does not treat the proposed probability as certain. More important to him is testing a deck they might actually carry into an unpredictable encounter. He therefore keeps cards that will do little against an ordinary arena monster, including snares meant for card-using opponents, two mystic cards, and a consumable Flee card. The utility cards include Stout, Blue Stuff, Greased Lightning, two Time Extends, and the consumable Combo card. The arena warning makes that last category consequential even in practice: using a consumable here would spend it.
Donut chooses a simulated 1980s shopping mall for the first medium trial. It has stores, multiple levels, shoppers, and staff who speak and occupy space. Carl had asked for an urban setting with familiar conditions, but he had not expected the simulated people to be physical participants in the scene. Once the pre-combat countdown locks the environment, he cannot have Donut remove them. As the fight begins, the civilian crowd reacts to the summons and later flees the monsters. Its presence makes the setting more than a visual backdrop; the practice fight occurs amid bodies, obstructions, and a changing field of movement.
Donut draws both Uzi Jesus and Shi Maria in her opening hand. Carl asks her to summon them together because he wants to learn whether the two powerful totems can cooperate. Uzi Jesus arrives with a seventy-five-second timer. Shi Maria appears with a two-minute timer. The experiment fails immediately: startled by the spider's arrival, Uzi Jesus fires at her, and she attacks him in return. Donut orders them to stop, but Uzi Jesus loses enough health to vanish before he can heal her. Their hostility wastes much of the value of drawing both cards together. It also reveals a problem that cannot be solved merely by choosing high-level totems: the personalities and reactions of summoned creatures affect the team's usable strength.
The mall's opponent is Rude-Dolph the Blood-Nosed Slay-Deer, a level-100 puppet-master accompanied by eight reindeer. He remains invulnerable while the eight puppets live. Donut summons Skylar Spinach, which splits into a flying donkey head and a spiked snake half after taking a hit. Its attack destroys one puppet. She buffs Shi Maria with Greased Lightning as the spider closes with the rest. Shi Maria turns several reindeer against one another, and the remaining puppets are killed. With Rude-Dolph's protection gone, she tears him apart. The victory is decisive, but it exposes another danger: Carl experiences a disturbing mental effect when Shi Maria opens her fifth eye, despite the arena's protections against generated mobs. He recognizes that the same power could threaten allies in an actual battle and thinks of the potion Mordecai is preparing for Mongo.
What repeated summons reveal
Further arena fights let Carl and Donut try nearly every pairing of their six totems. Shi Maria is by far their strongest attacker. She often ends an encounter quickly, sometimes requesting a look at Donut's hand or asking for buffs first. Her aggression also makes her hard to treat as an ordinary obedient card. In one fight she uses Raul as a weapon against a group of kappas. In another she prolongs an opponent's suffering instead of dispatching it at once. Her strength can win a simulation, but it does not give Donut full control over what happens after she is summoned.
Asojano likewise demonstrates the difference between power and reliability. On his first appearance in the arena, he attempts to cast a harmful effect on Donut. The arena's safeties stop him. Once she rebukes him, he follows directions and fights effectively, killing a squad of bomber pigs with a spell. Carl still distrusts him because the prevented attack shows what he tried to do when initially given an opportunity. The arena protects Donut in that instance while supplying evidence that his behavior may become a liability outside it.
Raul and Geraldo have a separate conflict. Both are useful combatants, but they insult one another when summoned together and once fight until Geraldo kills Raul. Donut can order Raul to stop, yet his compliance leaves him exposed when Geraldo continues attacking. Raul's own Bris spell is a strong ranged attack after a brief preparation, and Geraldo serves well in close combat when Raul is absent. The pairing shows why Donut cannot evaluate each totem only in isolation. A deck may contain two individually effective creatures whose shared presence disrupts a battle.
Skylar Spinach is comparatively compliant and largely silent. Its split form distracts enemies and attacks from two directions. Carl discovers an additional card interaction when the separated forms time out: they become distinct temporary cards for the remainder of that battle and can be summoned separately. Uzi Jesus creates the opposite sort of discovery. He sometimes promises to follow Donut's instructions and then fails to do so, even when she needs him to resurrect Geraldo during a fight with a minotaur. Donut eventually summons Raul to kill that opponent instead. Carl sees their string of victories as misleading evidence of readiness: they are defeating simulations despite gaps in Donut's authority over her totems, rather than because those gaps have been resolved.
The challenge unlock and opposing deckmaster
Carl and Donut eventually beat the paid challenge difficulty. Their opponent, Mushika, is a level-50 ratlike creature that Shi Maria kills almost immediately after appearing in their opening hand. Carl suspects that the result may have depended on killing Mushika before it completed a summon. The win opens Secret Challenge Mode, described as a medium-plus match against an opponent carrying a deck. These matches are free, but the pair may attempt them only three times. Their first such fight is therefore their first arena test of a deckmaster who can use cards against Donut, rather than a monster whose attacks are directed across the field.
The secret match takes place among grassy hills that block a clear view of the far side. Donut initially draws Raul as her only totem and summons him. The unseen opponent deploys wolves, then uses a mystic card to lock Donut's hand for thirty seconds. Another effect reveals the cards she holds. When Shi Maria enters that hand, the enemy plays a card that removes her from use for the rest of the battle. The enemy deckmaster, Der Schachmeister, then appears: a small boy whose deck has twenty cards, including six totems. His card replacement time is eight seconds, faster than Donut's observed ten-second interval. His combination of concealment, disabling cards, and quick draws directly attacks the assumptions that had made Shi Maria such a dependable answer in the ordinary simulations.
Raul destroys one wolf with Bris but is overwhelmed by the other. Carl keeps Mongo from engaging the enemy totems, reasoning that the arena's protection would make such a practice exchange unrealistically safe for him; in a real fight, Mongo and Carl could be hurt even where the deckmaster has special protection while a totem is active. Before Carl can send Mongo toward the opposing deckmaster, the surviving wolf reaches Donut. The simulation ends in failure and resets the deck. The defeat establishes that a strong totem in the deck is no defense when an opponent can prevent it from being played.
Carl's response is to reconsider speed and targets. He identifies the exposed enemy deckmaster as the route they should have attacked immediately, with Carl and Mongo acting while Donut managed her cards. He also wants faster, practiced commands for their own totems. The arena has shown them both what their deck can do and what it cannot yet do reliably: easy monsters and a rapid challenge victory concealed problems of timing, obedience, and hostile card effects that an opposing deckmaster made impossible to ignore.