Polterghast

Polterghast enters with X soul counters on it.
Polterghast's power and toughness are both
equal to the amount of soul counters on it +1

Soul Gatherer: each of the following abilities will unlock depending on how many soul counters this creature has
• Soul count 2: whenever a creature dies or enters polterghast gains soul equal to half of that creature's converted mana cost rounded up
• Soul count 5: Hexproof, Flying, Vigilance
• Soul count 7: Deathtouch, lifelink