For XRR, you get to smack any target of your choosing for X damage as an Instant. That’s decent enough on its own, since you usually don’t get X damage to any target as an instant- but we’re not done there. After you hit your target for that X damage, Electrodominance will also allow you to cast a card in your hand with converted mana cost X or less for free. So for X=5 you can throw 5 points of damage anywhere you want it, AND cast a 5-drop spell, all for the low cost of 5RR. It is cast, not play, so you can’t drop a land with Electrodominance, and anything you cast your opponent can counter if they so choose. After Electrodominance fully resolves, the ‘free’ spell will be on the stack waiting, and everyone gets priority. But there’s some caveats to your free spell!
To start with, Electrodominance’s free spell isn’t limited to Instants and creatures with Flash, even if you’re casting it during combat, or during an opponent’s turn. Because Electrodominance is giving you permission to cast a spell at a time you normally do not have permission (during the resolution of a spell!), you’re fine to cast Sorceries or Planeswalkers or Creatures or what-have-you. So an Electrodominance can blow out an attacking creature and slap down a big hefty blocker to stonewall another! Or be used to sneak in some damage and put out a big creature to swing with as soon as it’s your turn. Lots of fun things there. It won’t dodge ACTUAL timing restrictions, though- a handful of older spells have baked-in timing restrictions that tell you you can only cast the spell before or after a certain step in the turn. For example, you can’t free-cast a Berserk after Declare Blockers.
Electrodominance also only covers the ‘base’ cost of the spell. If there’s any additional costs like Kicker, you are permitted to pay them if you’d like to, but you do have to actually pony up the payment yourself. You aren’t gonna be casting Electrodominance for X=3 and casting a free, kicked Fight with Fire to do 13 damage on 5 mana. You could, however, do X=3 and freecast the Fire, then pay another 5R to kick it! Electrodominance also doesn’t play well with alternate costs, since you’re already using the alternate cost of ‘free’. So for Commander players out there, you’re not gonna Electro-Overload a Cyclonic Rift, whether you pay 2RR or 7RR, so keep that in mind.
Finally, we arrive at how Electrodominance works with other X spells: It doesn’t. Any time you’re casting an X spell via an alternate cost, if that alternate cost doesn’t define the value of X (for example, the Flashback cost on Increasing Confusion has an X in it), then X must be zero. So you can cast an Electrodominance for X=12 and have your free spell be another Electrodominance… but that second one will be for X=0, not X=10. So save it and hit them for another 10 next turn, neh?
Today’s Rules Tip was written by Trevor Nunez