Aeros, Heart Taken Flight

Aeros enters the battlefield with X arrow
counters on it.
{t}, Remove an arrow counter from Aeros: Target creature gains "Soulbond (You may pair this
creature with another unpaired creature when either
enters the battlefield. They remain paired for as long
as you control both of them.) As long as this
creature is paired with another creature, both creatures have lifelink and flying."