Powerstone

{t}: Add {c}{c}, this may only be spent to play
artifact spells or to activate artifact abilities.
{t}: Target with Crew gains 2 power points.
Equipped creature get "pay {c}{c} less to activate
it's abilities, to a minimum cost of {1}" and
"Crew 2: with Pay 1 power points: gets +1/+1
bonus."
Equip 2 (Powerstone may only be attached to
Artifact creatures.)