Mechanical saboteur, Uncommon 16b
Unliving. Runic. Siege.
Attack: 8
Enemy tower: -4
Wall: +N
N := damage dealt to enemy
This one's going to be problematic due to Siege. The game will calculate the 12 damage (and it will always be 12 damage unless the tower didn't survive the -4 after the 8 attack, in which case the game is over anyway) and add that to the wall during the turn. THEN Siege either will or will not deal additional damage to the opponent's tower, wall, or both. The keyword effect will occur after the card text's damage and wall gain are performed and no additional wall will be gained.
This is unfortunate since the potential Siege keyword damage adding to the wall increase is what makes this concept unique.
It's also worth asking whether this is intended to account only for damage done by this card or including damage done by Quick or Swift immediately prior. (I assume only this card, but that should be stated.)
It's arguably possible to have the card calculate (invisibly) how much damage Siege is ABOUT to deal and add that to the wall gain, but I get the feeling this might complicate things. We would then have to remember to address this card's code any time Siege's effect is tweaked, and that's a programming scenario Mojko has said in the past that he doesn't want to introduce.