Oh, I know you can do it by turn four with no fast mana, I was thinking in terms of Turn 1 kills.
Well for starters you can nix either the Desperate Ritual or the Pyretic Ritual. As Grinning Ignus + Birgi = infinite storm count by themselves. And the mana created by the Ignus results in 2R when you are ready to Grapeshot. The extra mana generated by Desperate Ritual at the end is just gonna be unspent RRR.
With your original combo if you swapped out the Grinning Ignus and Grapeshot for a Goblin Charbelcher. (R from Mountain and R from Spirit Guide to make RR, spend that for a Ritual to make RRR with an extra R from Birgi. Spend RR of the four R to cast second ritual to now have 6 R, cast charbelcher, this is another R for a total of 7 which gives you enough to cast it and activate it once.)
The main thing about foretell cards unlike suspend is that you can deposit your cards into exile for later use. Suspend is you do something similar but it eventually gets spat back out into play anyway.
The other aspect of utilizing foretell cards is that you are creating a rattlesnake situation your opponent can clearly see what your gonna do but they don't know when and have to play around it.
The demon's real power is gonna be a way to act as a sort of banking system for your nonland cards.
Lets say you have some janky combo that takes 5 cards, you got 4 pieces in hand already and the demon in play, you pay 8 upfront that turn to safely store your pieces. When it comes time to withdraw your cards and cast your combo, each card you deposited costs 2 less to cast. I use a jankier example as I figured it would only be natural for people to stop and think about trying to pay less for deposit which means having a more efficient combo that takes less cards.
Alternatively you can also consider this card as a hellbent enabler for cards like Infernal Tutor or Anthem of Rakdos. And like before, foretell means if the tutor or anthem were deposited, it can result in them getting a discount in casting cost to be B or BRR respectively.
Similarly you can also consider this card a way to avoid symmetrical effects that affect your hand such as Delirium Skeins if you are playing a Tergrid, God of Fright deck. Also useful if you have something you want to hold onto but you also have that typical dilemma with a Wheel of Fortune or Reforge the Soul in hand.
If you use Orvar with Whim of Volrath and a Memory Crystal on an Island, you get an untapped Island token which can then be tapped to cast another Whim of Volrath on it. As each time you target a island, you make a token of the island. Essentially blue can ramp with Orvar.
I think it personally just tarnishes the MTG image when they just wholecloth put existing IPs into the game today. Much of MTG's charm and clout was formed by how it reimagined existing things. P3K and AN exist, but they also come from an earlier of MTG.
This has a huge problem with misunderstanding. The ETB is fine but the attack trigger confuses the heck out of people because they won't understand why they can't attack.
This seems like a nonsense complaint especially when we have recent examples of that trigger like Uro, Titan of Nature's Wrath for example. And also not a single one of those cards using the original titan template have haste themselves so there should be no confusion on why a titan-esque card can't attack the same turn.
Which part of Uro creates tokens that the controller would expect to be able to attack with but can't? I would very much like to know because I've never made tokens with Uro so if you are, one of us is playing the card wrong. If you mean "Things can trigger on attack it's not complicated" I would like to point this entire conversation at you and say to the OP I have found the first person confused by your card.
Let me walk you through the problem so we are on the same page. When Titus enters the battlefield he will create a temporary Clong Legion of your field that you can attack with. This is a powerful and fun effect. Now next turn we attack with him and he once again creates a temporary Clong Legion. However, this new batch of temporary clones can't attack. Why? Because they were created in the declare attacker step after attackers have been declared. This is a confusing concept to the player because they will assume that the cloning effect is meant to give them attackers as it did the first time. I suggested that this functionality be changed the OP agreed which is why they posted a new card that doesn't create tokens on attack; though Kryptnyt's idea would have made a more powerful card the OP decided they wanted to keep it as an ETB over being repeatable.
Simple you don't need to fix it. In fact it encourages extra combat step cards like Aggravated Assault. Which means you would keep growing an army as long as you can keep getting more combat steps. Which provides a "build-around-me" feature and makes the card more interesting. And also you can use things that stop the turn such as Sundial of the Infinite to keep your army permanently.
This has a huge problem with misunderstanding. The ETB is fine but the attack trigger confuses the heck out of people because they won't understand why they can't attack.
This seems like a nonsense complaint especially when we have recent examples of that trigger like Uro, Titan of Nature's Wrath for example. And also not a single one of those cards using the original titan template have haste themselves so there should be no confusion on why a titan-esque card can't attack the same turn.
With your original combo if you swapped out the Grinning Ignus and Grapeshot for a Goblin Charbelcher. (R from Mountain and R from Spirit Guide to make RR, spend that for a Ritual to make RRR with an extra R from Birgi. Spend RR of the four R to cast second ritual to now have 6 R, cast charbelcher, this is another R for a total of 7 which gives you enough to cast it and activate it once.)
Hopefully that helps
The other aspect of utilizing foretell cards is that you are creating a rattlesnake situation your opponent can clearly see what your gonna do but they don't know when and have to play around it.
Lets say you have some janky combo that takes 5 cards, you got 4 pieces in hand already and the demon in play, you pay 8 upfront that turn to safely store your pieces. When it comes time to withdraw your cards and cast your combo, each card you deposited costs 2 less to cast. I use a jankier example as I figured it would only be natural for people to stop and think about trying to pay less for deposit which means having a more efficient combo that takes less cards.
Alternatively you can also consider this card as a hellbent enabler for cards like Infernal Tutor or Anthem of Rakdos. And like before, foretell means if the tutor or anthem were deposited, it can result in them getting a discount in casting cost to be B or BRR respectively.
Similarly you can also consider this card a way to avoid symmetrical effects that affect your hand such as Delirium Skeins if you are playing a Tergrid, God of Fright deck. Also useful if you have something you want to hold onto but you also have that typical dilemma with a Wheel of Fortune or Reforge the Soul in hand.
Snow is the true path.
Magus in the sheets
Turn 3 Giant Ox or Relic Golem, crew the plow, swing, play your actual 3 drop for the turn.