When playing Defy, do you know what unit is getting buffed before playing it?

Ruling: Yes, you know what unit is getting buffed and where it's going before playing Defy.

Sequence:

• When an ability (including those from spells) is put on the chain, you must declare targets for it to legally be played to the chain
• For Defy, this means declaring both the unit and the location as targets before the spell is played