When Anivia and Warwick attack a battlefield together, do they kill everything there, and can you choose the order their abilities activate?

Ruling: Yes, they can kill everything on the battlefield together, and you can choose the order their abilities activate.

Sequence:

• You must declare the order when the abilities trigger (not later)
• The abilities then resolve in the chosen order

Nuances:

• The order must be clarified right when the abilities trigger, not at a later point in resolution