Porphyric Haemophilia

Enchant creature.
Put two disease counters on enchanted creature.
At the beginning of your upkeep, remove a disease counter from enchanted creature.
As long as enchanted creature has one or more
disease counters on it, it gets -1/-1. If there are
no disease counters on enchanted creature, it
gains +2/+1 and lifelink, and is a black vampire
in addition to its other types and colours.