25 Jan 2019
Unbreakable Formation affects only creatures you control at the time it resolves. Creatures you begin to control later in the turn won't gain indestructible or vigilance and they won't get a +1/+1 counter.
12 Jan 2024
If an effect copies a spell with an addendum ability while it's on the stack, the copy wasn't cast at all, so you won't get the addendum bonus.
12 Jan 2024
Addendum abilities of instant spells apply while the spell is resolving, not immediately after casting it. If the spell is countered, you don't get the addendum bonus.