"If we cannot live proudly, we die so!"
—Eladamri, Lord of Leaves

Pandemonium

Whenever a creature enters, that creature's controller may have it deal damage equal to its power to any target of their choice.

The List

Tempest Remastered

Whenever a creature enters the battlefield, that creature's controller may have it deal damage equal to its power to target creature or player of his or her choice.

Time Spiral Timeshifted

Whenever a creature comes into play, that creature's controller may have it deal damage equal to its power to target creature or player of his or her choice.

Exodus

Whenever any creature comes into play, that creature's controller may choose to have it deal damage equal to its power to target creature or player.

The triggered ability does not check the creature's power until the ability resolves. If the creature is not on the battlefield when the ability resolves, it does damage equal to the power of the creature right before it left the battlefield. This means that if a creature enters which can destroy itself as an "enters" ability, the order of resolution of the triggered abilities does not matter.

If player A controls Pandemonium when a creature enters under player B's control, player A controls the triggered ability even though player B chooses the target and chooses whether to have the creature deal damage, which could be important if multiple abilities controlled by multiple players trigger.