Well since pratically Foehn blast furnance is the easiest thing to avoid in the game and is not very applicable atleast in multiplayer games, I suggest a replacement for it.
Suggestion 1: Basically a nanoswarm hive from Red Alert 3, it will act like a nanoswarm hive, nothing goes in or out, units inside the hive cannot be ordered to do something. and you have no need to build some defense structures so that it can easily be predicted and countered.
Suggestion 2: Some sort of support structure, usable in a 12x12 or 9x9 area, that buffs armour of units inside it for 12 seconds and for infantry, it gives them the same effect as a nanofiber sync, but no armour buff.
Suggestion 3: A gravity ball is shot into the sky and lands at the area ordered, it basically all nearby enemy units to it and piles them up, but has a greater than average cooldown for balans
Suggestion 4: paradrop 10 fin-alize pairs
These are rough ideas and I haven't had much time to think for them, so discuss I guess.