Zagan, Plague Baron.

Infect, and protection from creatures with Infect.
Pandemic - All creatures that are dealt
damage by a creature with infect gain infect.
Plague Harvester - Whenever a creature
with infect is destroyed add {b} or {g} to your mana
pool.
{t}{p/b}{p/g}: Sacrifice every creature with Infect
except Zagan, Plague Baron.