Naga Shaman

Infect (This creature deals damage to creatures in the
form of -1/-1 counters and to players in the form
of poison counters.)
{1}{g} Regenerate Naga Shaman.
{2}{g} Possess: Gain control of target creature. It
becomes a demon in addition to its other types. Activate this ability only at a time you could cast
a sorcery.