Arsenal Demon

At the beginning of your upkeep, or the upkeep of the controller of the creature Arsenal Demon is attached to, that player loses 4 life.
You may attach Arsenal Demon to creatures your opponents control.
Arm {5} ({5}: This creature loses the creature type and becomes an equipment. Attach it to target creature you control. It becomes a creature again if it's not attached to a creature. Arm only as a sorcery.)
Equipped creature gets +7/+7.