Mind Drain

Enchant player
At the beginning of the enchanted player's upkeep
put a syphon counter on Mind Drain then the enchanted player loses life equal to the number of syphon counters on Mind Drain and you gain that much life.
Remove 6 Syphon counters from Mind Drain: gain life equal to the enchanted player's life total then, their life total becomes 1. Exile Mind Drain.