The Cornucopia is a
Trinket Mage hit. If this environment wants something like
Darksteel Ingot, this is the one it wants.
If we're all in on the all creatures plan, maybe we could try
Thraben Gargoyle?
Or maybe we already have sufficient small artifact density and we could try out something completely different, like
Teneb, the Harvester. Good battlecruiser, that one.
Cube currently contains zero phoenixes. There are also few small-mid sweepers in red, but we probably don't want to completely hate out the tokens deck, so here's one that takes some work to set off. It also 'trades' with X/6s in combat, which is nearly everything, so the body is a little better than it looks in a vacuum.
I do think Black needs a giant reanimator target, for
Unburial Rites,
Rescue from the Underworld, and friends. It seems like most of the time you'll be casting reanimate spells for value rather than as your plan A, so whatever giant monsters you're playing have to be probably-castable in your probably-Black deck. I don't think it will singlehandedly end too many games, but there aren't very many creatures that are 'a little bit worse than
Griselbrand' so it could be rough to find a suitable replacement if it does turn out to be too good. My other suggestions for this slot are
Scourge of Nel Toth and
Demon of Death's Gate.
I like it when Green can remove creatures. If we'd rather Green just have another creature, I note that it could use a 6-drop, maybe
Rampaging Baloths? Plays well before and after a
Peregrination, synergizes with bouncelands, so on and so forth.
--maybe everything down here is too-early-to-have-this-discussion but whatever man, you don't control me--
Looking at the cube as a whole, I'd say
Rakdos's Return,
Assemble the Legion, and
Archangel of Thune (especially with
Spike Feeder but I like the Spike with
Well of Lost Dreams) are all on the strong side. Maybe the angel's fine, I'm not sure - it just advances the game to its conclusion more quickly than any of the other monocolored 5-drops. But then, what are our battlecruisers supposed to be? How many does each color actually need at this kind of cube size? Would it be obvious in a draft that you're supposed to take the big stuff? I guess I'm saying I think these three slots should be big(ger) creatures in the same color combinations.
Firemind's Foresight and
Mizzix's Mastery suffer from a low density of instants and sorceries, but maybe the latter is fine because it only needs one or two big spells to work properly. On the other hand, once you cross out the X spells, the spells that target other spells, the ones that already have recursion, and the ones that exile themselves, Red has 8 total targets, and that's counting
Stone Idol Trap which is frankly embarrassing at sorcery speed. Blue also has 8, but at least you can hit
Rise from the Tides, which does work as long as you didn't overload the Mastery. Yikes. Anyway, you're spending a card to flash back something like
Barbed Lightning at a mana penalty most of the time. I want, like,
Descent of the Dragons or something. Anyway.
Not sure where we should look for more White cards. I like
Faith Unbroken as a more-vulnerable version of
Journey to Nowhere, maybe it fits here somewhere.