Now demo is an odd one, in some cases his god tier, but others he lacks any actual use other than do splash damage, or if they run demo knight or a variant of the subclass, they aren't actually as useful as other classes.
A crit boosted demo with Scottish resistance against tanks is so overkill you can near enough stop tanks single handed, with this also being useful for zone trapping, let's put it simply, in two cities there are two ways the bots can go, and on low rounds they always enter the lower side, granting you the ability to set a sticky trap for them in that one area so they can't leave the spawning zones without getting obliterate from explosions, the second and third points are easier to trap, but makes your team lose valuable ground.
There are many places where demo-man can be good, but most of the time, he spy, medic and soldier have to sit it out so to not be a problem, but in the comics both soldier and demo-man were doing lots more than in game.
BINABASA MO ANG
Tf2 mvm custom guide
RandomThis will go over each class and give advice on what to equip, what is useful to run and the mistakes sometimes made in mvm games.
