New monsters for your 5th edition campaign.
It can be tough to run a solo boss encounter when the PCs have it outnumbered 6:1 with actions. The focused-fire principle often means that such encounters are embarrassingly short, unless you just make the creature a ridiculous bag of hit points. This PDF talks about ways to make your solo boss encounters more challenging, and more interesting, by giving it special traits which kick in at different times.
Written by James J Haeck. Illustrated by Ellis Goodson.