MTG - Does this do an infinite combo? Devil's play + Sevinne Chronoclasm + Geistblast from graveyard + Twinning Staff

Question

The situation:

1. I cast Devil's Play for x = 3.
2. I cast Geistblast for its copy effect from my graveyard.
3. Sevinne, the Chronoclasm triggers on the 1st cast from graveyard instant/sorcery - I get 1 extra geistblast, targeting the devil's play
4. Twinning Staff triggers - I get another Geistblast targeting the devil's play
5. I now have 3 geistblasts that copy devils play . So I get 4 instances of devils play
6. Twinning staff triggers again. I now have 3 possibilities:

A) - Devil's play gets copied only one additional time, for a total of 5. Because twinning staff reads: "If you would copy a spell one or more times, instead copy it that many times plus an additional time". Devils Play will get copied 3 times by the 3 geistblasts, thus it has already been copied 'one or more times'.

B) - Each of the 3 geistblasts is a new trigger for twinning staff so I get 3 extra copies of those 3 geistblasts for a total of 7 devils plays

C) - If B is true and A is false, then I could also make the "Sevinne geistblast" target the original geistblast for an infinite loop of "copy geistblasts". However, this infinite loop gets me no profit. But, because I have twinning staff out, each time a "copied geistblast", targets the original geistblast, twinning staff triggers, netting me 2 geistblasts each time. Half of them go towards the infinite loop, the other half go to Devil's play for infinite damage.

Which of these options is correct?

Answer 1

No, because Geistblast is not cast. Its ability

{2}{U}, Exile Geistblast from your graveyard: Copy target instant or sorcery spell you control. You may choose new targets for the copy.

is an activated ability, not an alternative casting cost. Therefore Sevinne is not triggered and your chain falls apart at step 3.

Answer 2

As the other answers indicate, Geistblast isn't cast from your graveyard so it doesn't have any interaction with Sevinne, the Chronoclasm.

But let's say we replace Geistblast with Increasing Vengeance (via flashback).

In that case, this is an infinite combo, as Sevinne + Twinning Staff gives you two extra copies of Increasing Vengeance with different targets. You can use those to copy the original Increasing Vengeance (which is lower on the stack), with each of those Increasing Vengeances giving you two copies of the original due to Twinning Staff. You can then repeat this process to get an arbitrarily high number of copies of Increasing Vengeance, at which point you can copy your original spell (Devil's Play) an arbitrary number of times.

Note that each iteration of the combo only gives you two more copies of an arbitrary spell. Copies of a flashbacked Increasing Vengeance only give you one copy from Increasing Vengeance plus one from Twinning Staff, not two plus one. See Will a copy of a flashed-back Increasing Vengeance still make two copies?. Given you only have two copies at each iteration, I personally prefer using those to copy the copier first and only copying the base spell once you have enough of the copiers, as exponential growth is awesome. You could also take the linear approach of creating one copy of the copier spell and one copy of the base spell at each iteration and then eventually create two copies of the base spell to end the loop.

Also of note, the key to this combo is Twinning Staff and two starting copies of a copier spell. Sevinne, the Chronoclasm is only needed to get things started and there are simpler replacements. You can do the following with Twinning Staff, Forked Bolt, and two copies of Fork for a combo I henceforth dub "The Silverware Drawer":

1. Have Twinning Staff on the battlefield
2. Cast Forked Bolt (the base spell)
3. Cast the first Fork targeting Forked Bolt (the copier)
4. Cast the second Fork targeting the first Fork (copy the copier)
5. The second Fork resolves, giving you two copies of Fork due to Twinning Staff. Have each of those copy the first Fork.
6. Repeat step 5 until you have 2^64 copies of Fork. (the infinite combo)
7. Have your 2^64 copies of Fork copy Forked Bolt. (end the combo)
8. Get 2^65 + 3 copies of Forked Bolt (the "+ 3" is from the original Forked Bolt and the first Fork plus Twinning Staff)
9. Deal 737,86,976,294,838,206,470 damage, divided as you chose (win the game)

Answer 3

The rulings on gatherer reinforce Philip's answer: When you activate Geistblast's ability, you are not casting a copy of Devil's Play.

When Geistblast’s ability resolves, it creates a copy of the instant or sorcery spell. The copy is created on the stack, so it’s not “cast.” Abilities that trigger when a player casts a spell won’t trigger. The copy will then resolve like a normal spell, before the original spell resolves but after players get a chance to cast spells and activate abilities.