It's better than the Deflecting Palm that they can counter 4 times with Pact of Negation and you just drop it on turn 0 and play your game plan otherwise (mana denial against them). Actually, now that I think about it, Angels Grace/Unlife just saves them and they ignore the Leyline.
This is viable because it's playable for 0. It's straight unplayable at 4 mana. It's far better than Kor Firewalker in the mirror, and it is not remotely as narrow. It wrecks 8rack. It might even be playable against a control deck to turn their removal into shocks. It turns all of BGx interaction into shocks.
No one is suggesting it's a main deck card, just sideboard. On it's face, it appears broadly relevant.
It will definitely deal 2 to Ballista's controller for every counter they remove, and the stack would look like: ballista ping -> leyline shock -> ballista ping -> leyline shock, with the Leyline shocks resolving before the corresponding ballista ping.
The new Leyline looks like it's a better alternative to Kor Firewalker in the mirror for when Burn mirrors get big. Incidentally, it's an uncounterable hate card against Storm and they're forced to bounce it and can't Remand it. It also can beat Lantern-style mill decks. As Tyler said, it can go in the extended sideboard part of the binder and wait until it's needed.
I think the answer is going to be 4. I'll probably stick to 8 fetches and cut 2 Vantage and 2 fetches to open up the spots. I'm going to wait on the price to calm down before buying foils though.
Philosophically, I like having some infinite combo in my deck so that it's possible for me to end the game so that we can play another.
If you play a lot of ETB creatures, Kiki-Jiki, Mirror Breaker is a synergy card at the base level and can combo with Pestermite, Deceiver Exarch, and Zealous Conscripts. Kiki in the yard plus Goblin Bombarment/Blood Artist+Sac Outlet/Purphoros, God of the Forge and Necrotic Ooze in play is an instant win, as well, though I only play Ooze. I have Kiki, Conscripts, and Pestermite as well as Mike-Trike in my deck. Imperial Recruiter can grab Kiki or Pestermite and Recruiter -> Kiki -> Clone Recruiter -> Pestermite -> Untap Kiki -> 10^100 Pestermites is doable for RRR with a Sneak Attack in play.
How about a recurring 2 damage for three mana? Specifically against control?
Control isn't generally a problem for Burn unless they build in a lot of life gain, so I don't feel compelled to play bad cards to solve an issue that doesn't exist. If I'm going to pay 3 mana for a card against control, it's Exquisite Firecraft.
3cmc cards have to be exceptional to play in Burn. This Chandra isn't good though for Burn.
M20 Chandra might have been worth it if it said you cast without paying (probably would have played 2, honestly). I don't want to pay 4 mana to recur a bolt and then 5 total for 2 of them. You have to be flooding to even play it (need 4 lands in play), otherwise you pay 3 mana to roll it up and do nothing, hope it lives a turn, and then get some use out of it. Cool card, but not good enough.
There are a lot of cards that were played before better alternatives came along, but that doesn't imply it's good enough today.
Hexdrinker is bad in Burn. It's better that Figure of Destiny, but it's still not good. Hexdrinker becomes a waste of a lot of mana when they Path it in response. Grim is pretty much guaranteed to deal damage to something if you untap with it, and it machine guns creature decks.
Seems like a bad idea to play a narrow card just to avoid getting curbstomped by fast combo (which is the kind of deck Burn can't handle, and if it's bonkers, I'd expect a ban). If they do something stupid and play Allosaurus Rider and pass, you can easily kill it. You can also Path Griselbrand or Skullcrack in response to the first activation.
That last bit is the part that I am not looking forward to. I just don't think it's right to take a perfectly viable current deck and nuke it from orbit because it's suddenly broken as a result of a fundamental change in the rules of the game. One could argue that such a deck was probably on the edge of broken before the rule change, but banning a deck because you changed the rules of the game doesn't sit well with me (looking at you, Duel Commander, for banning a bunch of Burn cards because they went to 20 life "to make aggro better" and made aggro too good). Legacy is probably safe, with good enough answers to the powerful combo decks that exist there. I don't think Modern is safe because the answers aren't good enough and they haven't done a good job incrementally curating the format with bans, which allowed decks to get to the edge/cross it without getting banned.
The new mulligan allows for certain decks to sculpt openers, while not benefiting other decks as much. It creates an unhealthy format, and the only way to remedy it is bans.
It's a complicated discussion with many facets, but I don't see how this mulligan rule is good for aggressive decks.
Well, since we can now mull for SB cards more efficiently, maybe we'll benefit from a full set of destructive revelry in the SB. I could see gutteral response serving a purpose now.
As a critical mass deck, we can't "efficiently" mulligan. Every mulligan you take adds another card you need to draw in order to win the game. Critical mass decks can't aggressively mulligan. Think of something like LED Dredge: I don't care how many cards are in my opener as long as I have a dredger, a draw, and mana and a "draw 7, put 3 on the bottom" mulligan to 4 is not a problem for that deck. You're going to lose if you can't blow up leyline and you're going to lose if you don't have enough burn spells to win. Both are bad outcomes for Burn, and the mulligan rule doesn't really matter for Burn. You can end up with a slightly less bad 6, but it's still bad.
What's Guttural Response do for Burn? Blue instants aren't what we fear. If you play GR to counter a counter, they accomplished their goal anyway: you spent 2 cards to deal 3 damage and that means their counter gained them 3 life. It's no different from burn spell -> counter -> burn spell.
Who will mulligan down to 5? A deck that can function on a few key cards. Tron, for example, is happy to take a couple shots at searching for a Tron+fatty. The Grishoalbrand deck is happy to dig for the key pieces of the combo. It's not that they're going down to 5 to dig, but rather that they're taking a look at a different 7 in search of 4 or 5 key cards within them. There used to be risk to mulliganing that low, but now there's essentially no risk. As a Legacy Dredge player, being able to get more looks at 7s is huge because I can dig for Dredger+land+draw spell far easier when I keep looking at 7s.
Burn doesn't benefit in the same way. You can't afford to dig for combo killing cards, because you could just lose outright because of it. The mulligan disproportionately benefits "key card" decks versus "critical mass" decks (we're the latter). The part that makes it bad for Burn is that decks can more aggressively search for Burn hate and still end up with a playable 5 or 6, whereas they previously could have had a hand that does nothing for their own gameplan but has Leyline. It means that the ones who were foolishly digging for Leyline aren't as vulnerable as before.
It's a complicated discussion with many facets, but I don't see how this mulligan rule is good for aggressive decks.
This is viable because it's playable for 0. It's straight unplayable at 4 mana. It's far better than Kor Firewalker in the mirror, and it is not remotely as narrow. It wrecks 8rack. It might even be playable against a control deck to turn their removal into shocks. It turns all of BGx interaction into shocks.
No one is suggesting it's a main deck card, just sideboard. On it's face, it appears broadly relevant.
It might be solid enough against Hogaak. They could just mill themselves enough to make a big enough zombie army to win in t4, though.
If you play a lot of ETB creatures, Kiki-Jiki, Mirror Breaker is a synergy card at the base level and can combo with Pestermite, Deceiver Exarch, and Zealous Conscripts. Kiki in the yard plus Goblin Bombarment/Blood Artist+Sac Outlet/Purphoros, God of the Forge and Necrotic Ooze in play is an instant win, as well, though I only play Ooze. I have Kiki, Conscripts, and Pestermite as well as Mike-Trike in my deck. Imperial Recruiter can grab Kiki or Pestermite and Recruiter -> Kiki -> Clone Recruiter -> Pestermite -> Untap Kiki -> 10^100 Pestermites is doable for RRR with a Sneak Attack in play.
Control isn't generally a problem for Burn unless they build in a lot of life gain, so I don't feel compelled to play bad cards to solve an issue that doesn't exist. If I'm going to pay 3 mana for a card against control, it's Exquisite Firecraft.
3cmc cards have to be exceptional to play in Burn. This Chandra isn't good though for Burn.
Hexdrinker is bad in Burn. It's better that Figure of Destiny, but it's still not good. Hexdrinker becomes a waste of a lot of mana when they Path it in response. Grim is pretty much guaranteed to deal damage to something if you untap with it, and it machine guns creature decks.
The new mulligan allows for certain decks to sculpt openers, while not benefiting other decks as much. It creates an unhealthy format, and the only way to remedy it is bans.
As a critical mass deck, we can't "efficiently" mulligan. Every mulligan you take adds another card you need to draw in order to win the game. Critical mass decks can't aggressively mulligan. Think of something like LED Dredge: I don't care how many cards are in my opener as long as I have a dredger, a draw, and mana and a "draw 7, put 3 on the bottom" mulligan to 4 is not a problem for that deck. You're going to lose if you can't blow up leyline and you're going to lose if you don't have enough burn spells to win. Both are bad outcomes for Burn, and the mulligan rule doesn't really matter for Burn. You can end up with a slightly less bad 6, but it's still bad.
What's Guttural Response do for Burn? Blue instants aren't what we fear. If you play GR to counter a counter, they accomplished their goal anyway: you spent 2 cards to deal 3 damage and that means their counter gained them 3 life. It's no different from burn spell -> counter -> burn spell.
Burn doesn't benefit in the same way. You can't afford to dig for combo killing cards, because you could just lose outright because of it. The mulligan disproportionately benefits "key card" decks versus "critical mass" decks (we're the latter). The part that makes it bad for Burn is that decks can more aggressively search for Burn hate and still end up with a playable 5 or 6, whereas they previously could have had a hand that does nothing for their own gameplan but has Leyline. It means that the ones who were foolishly digging for Leyline aren't as vulnerable as before.
It's a complicated discussion with many facets, but I don't see how this mulligan rule is good for aggressive decks.