Karona, False God

The five-color avatar nobody gets to keep: the upkeep clause hands the creature to whoever's turn it is, so it is permanently borrowed, never owned. That single line is the whole personality. A 5/5 with haste that switches sides every upkeep behaves less like a threat and more like a shared hot potato, and the tribal pump on attack rewards whoever happens to be holding it during their own combat step, not the person who paid all five colors to cast it. The design tension is genuinely strange: most legendary creatures are built to anchor a deck, while this one actively refuses to belong to its caster, turning it into a puzzle rather than a reliable payoff. The approach is to weaponize the donation rather than fight it, finding ways to control where she points when she lands in front of someone else. Because she untaps and changes hands on her own every upkeep, you are not trying to hold her so much as control where she points when she lands in front of someone else. Few cards translate a flavor concept (a deity worshipped by all and controlled by none) this directly into a mechanic, with the awkwardness of that translation being the point rather than an accident.