Aetherflux Reservoir

The first thing I thought of when I saw this card was the old "Fruity Pebbles" combo (Enduring Renewal plus Ornithopter or Kobolds of Kher Keep or any other zero-cost creature plus Goblin Bombardment), and/or the old Ravnica mainstay Cloudstone Curio. Technically you don't have to use it in a line of play where you use some elaborate setup to cast hundreds of spells in one turn, but I have a feeling that's mainly where it's going to be seen, at least for now. I'm intrigued by the fact that it also suggests an arbitrary-life-total situation; it's hard to think of a situation where you wouldn't just use it immediately to remove an opponent from the game, but there might be one I missed!

Constructed: 3/5
Casual: 5/5
Limited: 3/5
Multiplayer: 4/5
EDH/Commander: 4/5

Aetherflux Reservoir

This card got attention as an alternative win condition for Storm, thanks to both of its effects. While the "trinket text" at the bottom looks unattainable, keep in mind that a good turn can gain you a lot of life. Two spells is a net of 3 life, three spells gains you 6, and four spells would put you at 10. In a deck with a lot of cheap spells, that bottom ability is more relevant than you'd imagine at first and your opponents are not too likely to have life gain to try and outrace you.

That said, this is still a four-mana spell that usually has to sit on the table for a few turns before it really gets going. Most decks aren't going to want to go out of their way to put this down, but a control shell or Storm-style deck could get a lot of mileage out of this. (It also counts spells cast before it; if you cast a spell after this resolves, you'd get 2 life.)

I don't think this will be an all-star, but the decks that can use it will find this card a valuable weapon to play with, and they're going to love slamming this down.

Constructed: 4
Casual: 5
Limited: 2.75
Multiplayer: 3.5
Commander: 4