190
I fear what he's going to throw at us next fight
(ttrpg.network)
To be fair, they did get some pretty decent damage in on their surprise round. They just didn't get many more chances.
Give 'em hobgoblins; if I recall correctly, those guys have like 18 ac and teamwork abilities. They're also really low CR; my brother's party faced a group of them and could barely hit them. Cheap for sure, but a guaranteed difficult encounter.