I voted ghost seraphim, luminous charge, and phantasm.
Phantasm is the most obvious. Is an answer-or-lose card. At 2 mana. Thankfully, Abyssian has only 2 rushers. Regretfully, one of those two rushers is the best creature in the game. The interaction between the small buffing creature, often played in the backline and hard to reach, and Spectral Revenant is … unfun to say the least, and i won more than one game by hitting someone with a 14/6 revenant.
Imho, the buff should be a +1+0.
Seraphim is TOO MUCH VALUE. It’s a decently statted body, that then provides as soon as it enters the game anything, from 2 damage along a column (faie bbs), to game breaking effects like the reflection/wyrm’s aspect combo.
Imho, the spell should have a static reduction (like -4 cost), or a reduction to 2 mana, so you can’t plop down a seraphim and then go ham before 9 mana. It should also, imho, less health.
Luminous charge is the most obnoxious card in the game. Yes, it’s weak to lightbender. Yes, it provides food for thunderhorn. But it’s the definition of annoying; it’s a card against which you have to maneuver carefully, that you can’t attack, but that you have to whittle down because otherwise it will leave bodies for a winter wake. It also provides ENORMOUS burst with a skorn, and it can combo with Kara to provide walls that you can suicide into things. It’s, imho, too much.
A good chage would be to reduce the number of walls spawned, to at the very least 4, or even 3 with a cost reduction.