The question is how many HP should they have. Initially I figured just 1 (any hit would take them out) but I remembered there being a few wonky spells that get OP fast that way.
If the spells are the issue, fix the spell problem, not add a patch by having higher number of HP.
Remember what the reason behind minions is:
1. To fulfill the power fantasy of fighting many enemies
2. To fight many enemies without that being a hassle / the storyteller takes too much of combat time.
Of course a VTT does do tracking etc. for you. But combat flow is still a lot faster if a minion is just alive or dead (not having people to figure out which one is the damaged one and if they should attack that one or another one), not needing damage mentioned at all (its just dead if it hits). And especially having minions the same initiative makes many "ok next turn X" unnecessary, which just steal time. Storytellers tend to take too much playing time in combat anyway (compared to other players), so you want to reduce that time as much as possible, especially when you run a lot of creatures.
So my default answer is a minion should die after 1 hit/ 1 failed saving throw. No HP, just hit and dead.
I figure I want a single attack from one of the characters to likely take a knight down, but maintain the possibility that a terrible damage roll could flub it. So maybe 8?
So if we would want to do this, then I would make it for sure in a way that Martials cannot roll low, because they already have the disadvantage for not having area attacks. So at level 11 Martial characters should have +5 damage from strength/dex and a +1 magical weapon, so I would give the minions 7 health, that a normal martial will always kill them, but weak area attacks have some small chance to not kill them. (Of course if your martial players all have
I like the way minions are handled in "Flee Mortals!" (Any successful hit will kill one; if you go over the damage threshold, you can kill another one.)
The damage threshold of a minion at 11th level is 18.
Well this, however, does make minions a lot less special. One cool thing about minions is that "DPR" or "damage per round" does not really matter, which normally is king.
So that number of attacks and precision matters a lot more. If they have a threshold, now you want again high damage attacks, the same as you want fighting other enemies and let the exact same thing shine as in every other fight.