Soul Stone

Ongoing Spell — Buff • Cost: 2

Attach to a unit.
Attached unit gets +1/+1. If it would die, instead remove all damage from it and sacrifice all Soul Stones on it.

Black • Demonology Magic

Card-Specific Rulings

When the attached unit "would die," it doesn't actually die so things that trigger on "dies" such as drawing a card in the technician slot don't happen. — Sirlin, 03/02/16

If you Soul Stone something with Two Lives such as Justice Juggernaut or Garus Rook, then the first time it would die, it gets a crumbling rune from the Two Lives ability instead. The second time it would die, Soul Stone's ability triggers (effectively giving it a third life) — Sirlin, 03/02/16