Cleon
Legend
Quite a few fiends can summon others in 5e it just tends to be a variant ability. But I instend to later make a Murdaw phase 1 who is an enemy summoner (he summons evil armours which are basically helmed horrors, and creatures called Chop Clowns which I think a similar creature exists in 5e.)
That makes sense. Murdaw summons monsters in the game in the Second Battle via Call Servants, conjuring Prickly Pranksters (aka Chop Clowns) and/or Harmours (aka EvilArmors or Devil Armors).
Wow, those Evil Armours are hard nuts to crack - Defence 120! They're not that tough once you get through the shell though, having only 64 hit points.
Do Helmed Horrors have official 5E stats yet? I could only find Fan Conversions like this one, which looks about right to me.
I guess you can just use a Shield Guardian in a pinch.
Can't think of a similar creature to a Chop Clown offhand, but as it's basically just a fast stabby humanoid it'd be simple enough to reskin an Assassin or the like.