Something’s Denial 1UU
Instant
Counter target Spell

Investigate

They asked, and he said “no”.

Those 2-3cmc creatures generally provide a sizable upside if they live that outweigh the risk of them getting bolted. A confidant that lives quickly overwhelms opponents in card advantage, An electromancer that doesn’t die allows Storm to go off easier, Merfolk lords vastly increase the clock of their other creatures.

The bolt test is still a fundamental benchmark of the format because creatures need to have a certain “something-something” to them that outweighs the chance they just get bolted. That’s the primary reason Mantis Rider doesn’t get played, but Dark Confidant will.

Getting delirium up is definitely an issue for D&T/Hatebears, but in my experience an opponent that does not kill their creatures is an opponent that loses the game. Additionally, the fact that Topplegeist taps a creature as an ETB effect makes it not a dead topdeck, which is more than the other 1-drops those decks employ can say. I’d consider the Delirium a nice bonus that you’d get in grindy games, and most evaluate it as a 1/1 flier for W that taps something as an ETB. I think that’s enough to get it some run.

Sorry, this was unclear. As in, you need to rely on an opponent putting extra stuff in your yard, like blowing up your Vial or killing your creatures.

Sadly delirium will only check your graveyard. You’re on your own to get the 4 card types.

Love Topplegeist abstractly. Unfortunately, it’s much harder for the decks that want it (D&T, Hatebears) to activate delirium naturally. You basically need to rely on an opponent doing it, because those decks are going to be lucky to have lands and instants in their yard if anything at all.

That said, I am very excited to see delirium interact with tribal cards like Jordan’s favorite Peppersmoke and Tarfire. Maybe I’l start playing Warren Weirding again!

4+ toughness is definitely a benchmark, but there are enough 2-3 CMC creatures with <4 toughness that are still quite playable in Modern. Of course, all of them are heavily dependent on context. This doesn't even include one-drops, which CAN be Boltable because then you're at least just losing a creature at parity. Two drops like Blighted Agent, Goblin Electromancer, Merfolk lords, Steel Overseer, Dark Confidant, and many more all theoretically fail the Bolt test but give you enough contextual value that it's okay. This is why I'm less worried about the Bolt test in itself and more worried about the Tier 1 context (followed closely by mana cost).

Can't wait for delirium either! Early spoilers are very promising.

Or at least it was before modern went kaput and was replaced by the eldrazi format.

As BGx player, I’m looking forward to cards with the new dellirium mechanic. 4 card types in the grave is difficult at all.