I think the combined choices of restabilizing a board with draw engines, an extra +2 storm count in LED decks, a notable defense against aggro or a silver bullet attack combo and the ability to ramp +3 mana/+1 storm in LED after an untap or recur countered/milled/used combo pieces is a pretty gigantic package for a card which might have very little / zero deckbuilding cost for a lot of existing archetypes. Many other cards with flashback or graveyard value have been analyzed on the 'last knife when you're out of bullets' effect, giving you some means to claw back when you're in a stalled lategame state. But those cards all had up front opportunity costs. Lurrus can be all upside, an 8th card in hand that you draw every game. And when it can help power out ANT/TES combos or be its own value engine when goldfishing, then its not just a backup plan.
Just to put it into perspective, before breach was banned (yeah, derp), they were already running Sevinne's Reclamation in mainboards as a way to recur breach. This does it from the sideboard without needing to tutor it or get it into your bin with 5 mana. And with storm already having LED, Petal & Wishclaw as targets, it seems like too good a free 8th card to pass up. It might even convince more decks to run thinning baubles
So is this going to wind up banned in some formats?
This gives lots of eternal combo decks a disgusting level of consistency. You're not only starting with an 8th card in hand, but its a combo engine. You can cast this off black lotus or lion's eye diamond and then recast them the same turn, and the next turn, you'll have 6 mana available. In legacy you can cast LED -> crack LED -> cast Lurrus from sideboard -> cast LED from graveyard, next turn crack LED -> cast underworld breach from graveyard or crack LED -> cast LED from graveyard -> crack LED -> flashback past in flames with +1 mana open. All on top of whatever you're doing normally.
Burn decks with splash mana have basically 0 opportunity cost to run this, giving them extra lategame reach. All you give up is the protection of basic lands- already given up for RB- and you can start recurring goblin guides, eidolons, swiftspears, etc.
There are plenty of archetypes that can't slot this in, sure, like any stoneforge packages or gurmag angler, and combo has to give up simian spirit guide. But we're talking about deck building where black combo vintage archetypes would gladly give up their 1-of restricted necropotence if it meant having Lurrus in their sideboard recurring mox/lotus/chalice/vault/sol ring.
Just the fact you could have a completely empty hand and board in a long game with nothing but lands and mana rocks, and then cast this from your sideboard, then cast snapcaster from your bin, and use it to flashback yawgmoth's will, resolve a ton of rituals/rocks and pull a win out of nowhere- how nutty is that?
Just to put it into perspective, before breach was banned (yeah, derp), they were already running Sevinne's Reclamation in mainboards as a way to recur breach. This does it from the sideboard without needing to tutor it or get it into your bin with 5 mana. And with storm already having LED, Petal & Wishclaw as targets, it seems like too good a free 8th card to pass up. It might even convince more decks to run thinning baubles
This gives lots of eternal combo decks a disgusting level of consistency. You're not only starting with an 8th card in hand, but its a combo engine. You can cast this off black lotus or lion's eye diamond and then recast them the same turn, and the next turn, you'll have 6 mana available. In legacy you can cast LED -> crack LED -> cast Lurrus from sideboard -> cast LED from graveyard, next turn crack LED -> cast underworld breach from graveyard or crack LED -> cast LED from graveyard -> crack LED -> flashback past in flames with +1 mana open. All on top of whatever you're doing normally.
Burn decks with splash mana have basically 0 opportunity cost to run this, giving them extra lategame reach. All you give up is the protection of basic lands- already given up for RB- and you can start recurring goblin guides, eidolons, swiftspears, etc.
There are plenty of archetypes that can't slot this in, sure, like any stoneforge packages or gurmag angler, and combo has to give up simian spirit guide. But we're talking about deck building where black combo vintage archetypes would gladly give up their 1-of restricted necropotence if it meant having Lurrus in their sideboard recurring mox/lotus/chalice/vault/sol ring.
Just the fact you could have a completely empty hand and board in a long game with nothing but lands and mana rocks, and then cast this from your sideboard, then cast snapcaster from your bin, and use it to flashback yawgmoth's will, resolve a ton of rituals/rocks and pull a win out of nowhere- how nutty is that?