Phyrexian Altar

Sacrifice a creature: Add one mana of any color.

Intruder Alarm

Creatures don't untap during their controllers' untap steps.
Whenever a creature enters, untap all creatures.

Wily Goblin

When this creature enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Saheeli, the Sun's Brilliance

{U}{R}, {T}: Create a token that's a copy of another target creature or artifact you control, except it's an artifact in addition to its other types. It gains haste. Sacrifice it at the beginning of the next end step.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Altar of Dementia

Sacrifice a creature: Target player mills cards equal to the sacrificed creature's power.