Well, consider that Mindgate can copy various cards from the opponent's deck and you can use them against the opponent provided you have the right quanta.
From Entropy Adept you can get :
Note that I add the ability cost from Entropy Adept into the final cost for the card played.Chaos Seed - Decent CC that
may do about 2-3 damage. 3
spent.
Nova - 1 quantum for each element, possible rainbow. 2
spent (Almost like a half-Supernova)
Mutation - 50% Abomination , 40% Mutant, 10% dead creature. 4
spent.
Antimatter - Invert attack. 10
spent.
Butterfly Effect - Target a < 3 attack creature and give it
Destroy. 7
spent.
Pandemonium - Random effects to all creatures.
Fire bolt, Ice bolt, Freeze, Gravity Pull, Shockwave, Sniper, Reverse Time, Drain Life, Infection, Lobotomize, Lightning, Parallel UniverseMost likely damage occurs. 5
spent.
In general you'll probably get a CC spell (Chaos Seed, Mutation, Pandemonium, Antimatter) or a buff card (BE,Mutation).
Technically it's CC on a stick similar to Arctic Squid and Vanadium Warden but it costs the same/more and is unreliable since you may have too much quantum or get the wrong card.
From Entropy Sage you can get :
Note that I add the ability cost from Entropy Sage into the final cost for the card played.Chaos Seed - Buff of +1-5 | +1-5 . 3
spent.
Supernova - 2 quantum for each element, possible rainbow use. 4
spent
Mutation - Random Mutant. 5
spent.
Antimatter - Invert attack. 8
spent.
Butterfly Effect - Target a < 3 attack creature and give it
Destroy. 6
spent.
Pandemonium - Random effects to all enemy creatures (See unupped list for possible effects). Most likely damage occurs. 7
spent.
Overall most cards end up being more expensive w/better effect or slightly less expensive. It's slightly more buff-focused since CC is now limited to Panda and AM which is 7 or 8 quanta total.
Although the spells are technically "unlimited", they are also unpredictable - similar to Mindgate, you may not get the card you're expecting or that you need. It's also more unreliable than Mindgate because at least with Mindgate you can obtain select cards like Towers and Creatures multiple times but this will give you a different spell with multiple uses, and they may not be the one you want. This card is also vulnerable to CC, so it seems balanced to me.
I would like Oldtrees's opinion on this.