Mjolnir

Hexproof
Equip {2}
Equipped creature gets +2/+0
If equipped creature is Thor, God of Thunder
or Rune King, Thor, equipped creature gets
+4/+3, flying, and has,"{1}:Unequip Mjolnir,
then exile it. Target creature an opponent
controls is dealt 3 damage and becomes tapped.
Return Mjolnir from exile at the beginning of
your next upkeep and equip it to the previously equipped creature."