Varin, Genius Inventor

Whenever Varin crews a vehicle without +1/+1 counters on it, put a +1/+1 counter on that
vehicle and a knowledge counter on Varin.
Vehicles spells you control cost {1} less to cast per knowledge counter on Varin.
{t}, Remove X knowledge counters from Varin:
Return target vehicle with converted mana cost X
or less from your graveyard to the battlefield.