Portcullis 
Artifact
Whenever a creature enters, if there are two or more other creatures on the battlefield, exile that creature. Return that card to the battlefield under its owner's control when this artifact leaves the battlefield.
click a line to search just that ability, click more to combine them
Cards that do something similar expected a card that isn't here?
Reports become test cases the matcher is graded against before an update ships. Delvefall isn't a chatbot guessing, it compares the printed rules text of every card with plain math, and examples like yours decide which differences should count.
Mirror of Life Trapping 86%
$0.34#11106
"Whenever a creature enters, if it was cast, exile it, then return all other permanent cards exiled with this artifact to the battlefield under their owners' control."
Saltskitter 84%
$0.23#15050
"Whenever another creature enters, exile this creature. Return this creature to the battlefield under its owner's control at the beginning of the next end step."