You know what I like? Huge creatures, gaining life, drawing tons of cards, and interesting rules interactions.

You know what I love, then? Hydroid Krasis.

Hi everyone! I hope you’ve been enjoying the pre-release for Ravnica Allegiance! I certainly have, because it gives us a whole new set of interesting cards to talk about, including the best Jellyfish Hydra Beast in magic, Hydroid Krasis. Without any further ado, let’s get into it.

First of all, let’s look at that triggered ability. This is a somewhat uncommon cast trigger rather than an enters-the-battlefield trigger; that means when you cast the Krasis, the triggered ability goes on the stack on top of the Krasis itself, so the trigger will resolve (and you’ll gain the life and draw the cards) before the Krasis enters the battlefield. The trigger doesn’t care about its source- even if the Krasis eats a counterspell, the trigger is still going to resolve, so you get that value regardless. Assuming you cast it for more than X=1, but that seems like a safe assumption.

Speaking of X, let’s get to the tricky part: Hydroid Krasis’ converted mana cost. There are a lot of cards in standard that care about what the converted mana cost of a creature or spell is, and it’s worth knowing how they work, so here’s the bottom line: Everywhere but the stack, X is 0.

That’s a little weird, so let’s get into some examples. First example, Disdainful Stroke. Disdainful Stroke will counter a spell with converted mana cost 4 or greater- so if you cast your Krasis for X=2 or more, it’s at risk of getting Disdained out of existence. But the trouble is just beginning for our poor Krasis, because as soon as it’s entered the battlefield and gained its counters, it forgets what the value of X was when it was cast, so it’s CMC goes right back down to 2- so no matter what you cast it for, it’s vulnerable to a Ritual of Soot!

This holds true for anything looking at the CMC of the Krasis when it’s anything but a spell on the stack- whether it’s looking on the battlefield (like Prime Speaker Vannifar), your library (Ruin Raider), or your graveyard (Gruesome Menagerie). As far as all those cards are concerned, it’s just a two drop.

Worth noting- X is not determined by what you pay when you cast Krasis, but the other way around. You declare a value for X, and use that number when you’re figuring out your total costs. This means that a copy of The Immortal Sun lets you get a ‘free’ +1 to X (because a Krasis for X=5 would end up costing 4UG instead of 5UG, for example)! It also means that something like Damping Sphere costs you extra for no value- a Krasis for X=4 with a +2 Damping Sphere tax may cost you 6UG to cast, but you’re only gaining and drawing 2, not 3.

Finally, a warning. Like we learned on Monday, casting your Krasis for free, or having it enter the battlefield without being cast, will set the value of X to 0. This will likely not be survivable for your poor Krasis. You have been warned.

So that’s all for this week. I hope you enjoyed this Krasis care guide, and I wish all of you the very best in huge creatures, life gain and card draws until we meet again. Ciao!

Today’s Rules Tip was written by Alistair Crook