Their power was so great they were restricted or banned in most formats
(When it dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.) Instant Color tag templates(None) Unhallowed Pact Enchant creature When enchanted creature dies, return that card to the battlefield under your control
If your opening hand feels too weak, or is outright unplayable due to a lack of lands, you have the chance to take a mulligan and draw a new one that might be better
You've also got Regeneration (Boneknitter), graveyard love (Corpse Connoisseur), graveyard hate (Crypt Creeper), life loss (Organ Grinder), tutoring (Corpse Harvester), edicts (Fleshbag Marauder), Necropotence variants (Graveborn Muse), and can even destroy the occasional enchantment (Quagmire Druid)
Ive even used elves like Birchlore Rangers to hard-cast Atraxa, which is emminently doable at seven mana