Is there another modern card that functions like Intruder Alarm in that I can untap a creature if another creature comes into play. I know there are plenty of creatures where I can tap it to untap another. But those don't combo well.
There is not a copy of intruder alarm in modern... or in magic I believe. However, if you are making a funzies deck you could make some convoluted combo that does the same thing. Like cloudstone curio, 3 mana dorks, and 2 village bell ringers. But generally 6 cards combos dont tend to see competitive play.