Stupid Idea Time!
Spy has a Sapper yeah?
In the military, Sappers are dudes who blow shit up right?
Therefore give the Spy Satchel Charge as a Sapper Replacement.
You light it, toss it, it ticks away for a little bit, then explodes.
Does 100 Damage, Sticks to buildings, Does double damage to a building it's stuck to.
So that'd leave any stuck building >L3 Dead, and anything =L3 Left at 16 health, ripe for a revolver shot.
Plus a bunch of wounded buildings/people if they're caught in the blast.
You could toss it and Satchel Jump with proper timing. (Dat Advanced Mobility)
Throw it in a crowded Enginest to damage errything and errybody (No need to get in melee range of 3+ Engis)
Works without buildings on the enemy team (Dat sapper that works without engineers)
Is probably unbalanced and Dumb as hell (Why am I posting this)