Monster Styles expire because transformations are temporary dungeon resources. Their floor-based Style Limit decreases as you descend. Switching back to Zombie form does not make a borrowed monster Style permanent, and returning to level 1 on a new dive is a separate part of the run structure.
Plan around a limited transformation
Davy's Zombie form remains available, while acquired monster forms last only for their allotted floors. You can switch among the Styles you have during that period without spending a limited number of swaps. The limit follows floor progression, so do not plan an entire dive around keeping the first useful transformation forever.
Replace deliberately
When a new elite core offers another Style:
- Check the current transformation's remaining duration in the interface.
- Consider the next encounter or route you want to take.
- Compare the new card's actual skill and stats with what you are using.
- Accept the replacement if it supports the next part of the dive better.
A familiar monster name is not enough to judge the replacement. Another core from the same enemy type can carry a different active skill, so inspect the offered ability before accepting it.
Keep a fallback for the next encounter
A flight-capable form may be valuable for a particular movement task, while a heavy attacker can be more useful in another fight. Spend the remaining floors on a concrete purpose rather than saving the form indefinitely.
If a transformation vanishes after its floor allowance is used, that is expected behavior. If it disappears earlier than the interface indicates, record the displayed duration and the transition where it happened; the normal expiry rule alone does not establish that a separate fault has occurred.