Illuna, Apex of Wishes mutation ability issue
When Illuna's first non spell card is a creature and that creature is not already on the board it is immediately destroyed/exiled/vannished after entering the board. In case that creature already exists on the board it is reinforced as it should be.
To test this: create a deck with 7 spells and 3 creature, so that every fetched non spell card is a creature. I used brokhan for this, Sample video available.