Krampus, Punisher of Helheim

Whenever a creature is tapped as an effect of a spell or ability, each player creates a Coal artifact token with "{t}, sacrifice: add {c}"
If a player has 4 or more Coal artifacts at
the beginning of their upkeep, spells cost {b}
more to cast.

...As the Claw passed over the threshold, the air wore death like a cloak...