Water. Earth. Fire. Air. Long ago, the four nations lived together in harmony. Then, everything changed when Wizards of the Coast attacked and turned the nations into cardboard rectangles. That’s right, folks, we’re riding our sky bison into another Universes Beyond set, this time featuring one of the best cartoons Nickelodeon’s ever produced. This set has fewer Missed Trigger upgrades than most, but they’re still worth talking about! Ready, gaang? Yip yip!
Four cards have one or more triggers that upgrade to a Warning when missed:

“[Whenever you attack, make a token]. Sacrifice that token at the beginning of the next end step.”
“[Make tokens]. At the beginning of your next end step, sacrifice those tokens.”
This set’s tried and true “make a token and get rid of it later” triggers, but this time they’re in black instead of red! As usual, having more creatures is better than having fewer. If a player forgets to sacrifice the tokens either of these triggers created in the end step, they’ll earn a Warning.
“Whenever a player casts a noncreature spell, they lose 2 life.”
This symmetrical trigger doesn’t care who does the spellcasting, just that they’re punished for doing so. If a player forgets to remind their opponent to lose life, no harm no foul. But if that same player forgets to lose life when they cast their own Energybending or some other noncreature spell, they’ll earn a Warning.
4. Tiger-Seal
“At the beginning of your upkeep, tap this creature.”
A 3/3 for one mana is great, so of course it comes with a bit of a drawback. Forgetting to tap this creature at the beginning of your upkeep will earn a Warning. Of course, note that if the creature is already tapped, you don’t need to acknowledge this trigger at all.
Two notable cards have a trigger that does NOT upgrade when missed:

“When this creature enters, mill two cards.”
Self-mill can be considered generally detrimental, but not in this case. Platypus-Bear’s last ability directly benefits from having more cards in the graveyard, so the self-mill trigger is not detrimental in this case.
“Untap this artifact during each other player’s untap step.”
This one’s not a trigger at all! If a player forgets to untap this artifact during another turn, treat it like a Game Rule Violation.
Much like the show it’s named after, this edition of the Missed Triggers Guide is a little short. But also like the show, we’ll have a Missed Triggers Guide sequel in a few months! We’re making a thrilling return to Lorwyn, of all places. I’m of two minds about it.