Something for my Mazirek EDH and I'll give a nice reference to older cards...
Offerings to the Pit- Enchantment 1BB
Whenever a creature enters the graveyard from the battlefield for any reason, it is considered sacrificed.
Whenever a creature is sacrificed, put an offering counter on OttP.
If OttP has 5 or more counters it gains:
Pay 2BB, create a 4/3 black Demon Bird creature with haste, flying and first strike
If Ottp has 10 or more counters it gains:
Pay 5BB, create a 7/7 black Demon with haste, flying and trample and, at the beginning of each opponents upkeep that player must sacrifice a creature they control, if they cannot, this creature deals 7 damage to them.
Offerings to the Pit- Enchantment 1BB
Whenever a creature enters the graveyard from the battlefield for any reason, it is considered sacrificed.
Whenever a creature is sacrificed, put an offering counter on OttP.
If OttP has 5 or more counters it gains:
Pay 2BB, create a 4/3 black Demon Bird creature with haste, flying and first strike
If Ottp has 10 or more counters it gains:
Pay 5BB, create a 7/7 black Demon with haste, flying and trample and, at the beginning of each opponents upkeep that player must sacrifice a creature they control, if they cannot, this creature deals 7 damage to them.