If Caitlyn (who has an ability that says she must be assigned damage last) is given the Tank keyword (which says she must be assigned damage first), what happens?

Ruling: When Caitlyn has both her ability (assign damage last) and Tank (assign damage first), she has two conflicting requirements. You satisfy as many as possible, meaning the opposing player gets to pick whether to assign Caitlyn damage first or last (but not in the middle).

Nuances:

• This is not a layers issue because both abilities exist on the unit simultaneously; layers determine the order continuous effects are applied, but the object still ends up with both abilities
• The conflict is resolved by satisfying as many requirements as possible, similar to how other TCGs handle conflicting requirements and restrictions