One of the exciting new archetypes Theros brings to the Standard format is Red/Green Monsters, highlighted by such fearsome creatures as Polukranos, World Eater and Stormbreath Dragon. Something you might not have noticed about the titular monstrosity mechanic is that other than the mana cost, there are no restrictions on when you can activate the ability. That means that if you have the mana, you can activate it as many times a turn as you want. You can even do it on your opponent’s turn!

However, there’s a special quirk with the Monstrosity ability that works differently from other abilities; the first successful resolution, in addition to putting counters on the creature, causes it to “become monstrous.” A creature can only “become monstrous” once as long as it stays on the battlefield, and if a creature’s already monstrous at the time that its Monstrosity ability tries to resolve, it won’t do anything. Ordinarily, you wouldn’t want to bother with activating a Monstrosity ability more than once, but let’s look at an example of when it might be good to do so.

You’ve got a Stormbreath Dragon and a lot of mana. After you activate the Monstrosity ability, your opponent responds by attempting to kill the Dragon with a card like Volcanic Geyser for 4. If the Dragon dies before Monstrosity resolves, it won’t gain any counters or become monstrous, so its last ability won’t trigger. But what happens if you activate Monstrosity in response to the Geyser? First you’ll put three +1/+1 counters onto the Dragon and it becomes monstrous, causing its last ability to trigger and eating a chunk out of your opponent’s life. Then Geyser resolves, dealing 4 damage to the now 7/7 Dragon. The first Monstrosity ability is still waiting to resolve, but your Dragon is already monstrous, so it disregards the rest of its effect. No new counters will be added to the Dragon and no additional damage will be dealt to your opponent, but at least your Dragon is still alive!

Today’s Rules Tip written by Jen Wong