Mjolnir

When Mjolnir comes into play, you may equip it to a creature. All creatures take 1 damage.
Equip {5}: Equipped creature gains +2/+0 and gains +1/+0 for each charge counter on Mjolnir.
You may pay {x} to put X number of charge counters on Mjolnir.
If equipped creature attacks or blocks, remove all charge counters from Mjolnir.