Ideas can be found anywhere, don't they? Still, I should be commenting...
Sweeper Van: Some way of reactivating an ability has been suggested many times already, and how you have done this sounds... a bit costly. Sure, specific circumstances can make it deadly, but... 9 Time for first use is much. I'd drop the insummon to 5 and ability to 2.
Mirror Image: Sort of a funny card, as it pretty much negates the possibility of copying a card to get its high attack. Still, could be useful on cards with abilities that you want to be tougher, except that abilitied creatures usually have HP higher than attack ass well. Some problems would happen with variable-stat creatures, like the Scarab or Hayeses I suggested - when a Scarab gets mirrored, does it retain up to 6-12 as 6-12 attack and then change the 2-3 (no Devours in this for less contusion) of former ATK value into higher, swarming HP?
Oh, and ignore those people who start throwing Flying Titan Abuse at you and tell them to pack a Maxwell's.
Oh, and Mirrors belong to Light originally, and if it was possible I'd make this card dual, somehow, but it can't be and it's fine that way and easier to program as well.
Cerberus: Percentage, so... it goes up to 100, or what?
Ship Shade: Yeah, yeah, persisting, Bloodshadow made CockRoaches a lot of time ago, your version is bit cheap, up the cost to 4, think of Blue Crawlers how must they suffer when a creature is straight better than them.
Or lower the HP to 2.
Jupiter: This card has many uses, and I'd say it is just right, even though the stats could be a bit lower, like 2/9, IMO, compare to FFQ, and the ability cost could be lower, as it doesn't do much, really, but still.
Hexing Hag: This creature is durable. 2/4 provides Paradox immunity, basic highhpness that lets it survive a RoF or a Snipe, and so on. This creature has a killer ability that is pretty reliable when it comes to disabling creatures, for it works like a Neurotoxin while still allowing crashing against a Fire Shield. And yet, it doesn't cost much. 5 to summon? Low. 3 to ability? Sure, here it is higher, but Life tends to have much quanta with Rustlers and general cheapness of creatures. So, I'd do the following: Raise the insummon cost, lower the HP to 3 or so, and possibly nerf it a bit more somehow. And remember: Instantly reducing a creature to 1 HP should NEVAR be an ability. Unless it's something real costly and Paradoxable.
Frog: 1. How would the game remember what was it?
2. Against a Fire Shield this thing is really borked.
Seventh Heaven: Remind me what immobile was. The card's balance... then I'll be able to check it with my opinion.
8Ball: And the funniest thing you can kill it yourself, making it cheaper than Uns... wait, what is the cost?
Stitch in Time: Seen the movie. Bedsides, this card seems to be a typical last save, just absolute... you might want to make it enchanted so it is real absolute, or add this to the upgrade, at least, as otherwise it's no better than a Dimshield which works for 3 turns and costs just 6 Aether.. A save card like this seems like it's needed somewhere, and it's a nice boost to Mono-Time.
Perfection: Normalize costed 3 Aether in some older thread and I liked it more that way. As you can see, suggested over and over, and your version is too costly.
Upcrank: By applying a status, I presume? Made something like that, was called Power Trade and did same thing just Darkness in element, and stopped when reaching 1 HP... Well, here we get to the flaw. If I had something with high enough HP to play this on so it survives several turns, I'd rather Rage Potion. (Made Power Trade before Rage Potion, so...) If I didn't have any, like Fire, then it'd be useless... unless you're suggesting Lava Golems here, in which case it'd have a pretty nice but still a limited use.
And if it was used to deal damage, then an Infection with a buff should cost less, right?
Witching Hour: Not sure if that's doable, but generic "lower playing cost" cards do seem like a good idea. Not sure what could this be used for, though.
Murphy: If not faced against some spell cards, it's useless. If it is, it's terribly effective. So, I'd say... Purify's Fate. (situationally awesome but won't get any use 'cause it's too situational)
Quarter-Life: By the time you can spend 7 Life on this thing you'll have enough proper quantum sources to make playing this not pay back, as you could do without it... bedsides, Life does not simply need some quanta stockup. I'd say a Fire version, or a Darkness one, would be useful, but then...
Golem XV: Compare the cost and stats to a Stone Dragon and tell me what do you find. Also, well... the ability can offset some single poison counter, and Snipes, and such, except that with its 8 HP it's more likely to be attacked in such a way that won't leave it until the end of the turn. Up the cost or lower the stats. Heck, lowering the stats to the point of lowering the cost would make it sort of more useful, for some reason.
