­Heart Warden + Flywheel Relic

Another mana maker pair! Here we've got a really freakin good one; a cycling-from-the-battlefield elf, and a really strange one, from a set that introduced the incredibly parasitic idea of a while basket of new mana symbols; though they are at least alternate payment types, not required. Here we see an example - this can make torque for free, or for pain; making it a talisman or signet variant.

So. CMC2, mana maker that also does something extra.

My instinct is that if I'm aiming for powerful, it wants to cost ; and if it's doing that there's no point it being a mana fixer it needs to outright make a lot of mana.

I think we'll make this a burst of mana, rather than ongoing mana.

Eh. Probably overshot.

Generally, these days, green gets ongoing mana and red gets burst mana. Blue... doesn't do either, really. If you wanted to add blue to a green mana maker... I guess I'd go for some kind of untap trigger, or something.

But yeah, I think you did overshoot somewhat. Spending 3 to get 7 is a bit too much better than Seething Song! You could make it give just 2 mana, at which point the ETB trigger is reminiscent of Burning-Tree Emissary but the other effects make it scarier (in exchange for being smaller and harder to cast).

You're right; this is insane if you just cast then sacc immediately.

Nerf-bat incoming.

Another option I wondered about mentioning was to add to the sac ability. That way this (using the old wording) would be a Pyretic Ritual when it entered, and a Dark Ritual when it left, but those wouldn't normally be the same turn.