Aryn, Guardian of the Feather

Oath {w} (Whenever this creature attacks and isn't blocked, you may pay {w}. If you do, put an oath
counter on it.)
When Aryn, Guardian of the Feather enters the battlefield, create two 1/1 white and blue Bird creatures with flying, Crew 1 and "this creature
can't attack unless it is crewed. This creature can
only be crewed by creatures with oath counters
on them".