A ball of clay rolling down a workshop bench. Everything you roll over sticks to you, every gram makes you stronger and clumsier, and the last gate always wants you small.
Your spells are relics that shatter permanently when used. The strongest one in the cathedral has a single use — power here is a consumable, not a stat.
Every guard is blind to exactly one colour, and that colour is the only thing you can hide in — so cover is never cover, it is cover from one specific person.