Mjöllnut

Sentient — Whenever Mjollnut becomes attached
to a creature, flip a coin. If it comes up heads,
that creature becomes a 1/1 green Squirrel
creature for as long as Mjollnut is attached to it.
Equipped creature gets +2/+2 and has trample.
If it has base power and toughness 1/1, it gets
+4/+4 instead.
Equip {g}{g}