Power Word KillBBB
Instant
This spell can't be countered.
Put target creature with toughness 5 or less into the graveyard. Die.
There are no cards which say "target creature dies" (because 'dies' is not a keyword action but is the same as 'put into the graveyard from the battlefield' but I'm getting off track). It is almost the same as sacrifice, so it could say "target player sacrifices target creature they control" but that doesn't fit the flavor. Some similar cards are Strangling Soot and Sudden Death. I think 3 toughness is the best approximation of 100 hp in D&D, but the spell needed to be more powerful.
Unfortunately, Wizards has beaten you to the punch on Power Word Kill
This is an interesting effect, though this is effectively just a Dismember since it gets around indestructibility and regeneration the same way -5/-5 does.
Power word kill is just silly. It can kill a God, Giant, Kraken, lLviathan, Beast, etc. Some have arguably more health than the ones this one doesn't kill.
Instant
This spell can't be countered.
Put target creature with toughness 5 or less into the graveyard.
Die.
There are no cards which say "target creature dies" (because 'dies' is not a keyword action but is the same as 'put into the graveyard from the battlefield' but I'm getting off track). It is almost the same as sacrifice, so it could say "target player sacrifices target creature they control" but that doesn't fit the flavor. Some similar cards are Strangling Soot and Sudden Death. I think 3 toughness is the best approximation of 100 hp in D&D, but the spell needed to be more powerful.
This is an interesting effect, though this is effectively just a Dismember since it gets around indestructibility and regeneration the same way -5/-5 does.
"Choose a creature. That creature's controller sacrifices it."
Gets around a lot of protections.
Dunes of Zairo
SHANDALAR
Innistrad - The Darkest Night
~THE RAVNICAN CONSORTIUM~
A Community Set
Commander: Allies & Adversaries