Ophiomancer gives black sacrifice decks a steady supply of creatures without asking for more cards or mana. At the beginning of each upkeep, it creates a 1/1 Snake with deathtouch if you control no Snakes. That includes opponents' upkeeps, so a four-player game can provide several tokens per rotation when you have a way to sacrifice each Snake before the next turn begins.
Viscera Seer turns those tokens into repeated scries, while Ashnod's Altar converts them into colorless mana. Pairing Ophiomancer with Skullclamp is particularly efficient: the Snake's one toughness means equipping it normally sends it to the graveyard and draws two cards. Blood Artist and Zulaport Cutthroat add life-drain rewards whenever the tokens die, making the card a useful supporting engine for aristocrats commanders.
The deathtouch body also matters when you are defending. Leaving a Snake available can discourage an attack from a much larger creature, allowing you to choose between preserving a blocker and cashing it in for another resource. Ophiomancer itself can remain safely behind the front line while the expendable token handles combat.
Watch the upkeep timing carefully. You must control no Snakes both when the ability would trigger and when it resolves. Sacrificing an existing Snake after your upkeep has already begun will not create a missed trigger. Clear it during the previous end step when you want the next upkeep to produce a replacement.
