The PH has a suite of summoning spells, with more on the way in Xanathar's Guide, and the wizard and druid are both adept at using them.
— Jeremy Crawford (@JeremyECrawford) October 1, 2017
Summoning is a nasty little problem in terms of power, balance, compexity, but one we've been pondering on and off for a long while. https://t.co/FJklTgAB4a
— Mike Mearls (@mikemearls) October 1, 2017
Maybe the solution is to make summoned monsters not behave like monsters but rather as targeted or area effects.
— Dee (@FarthingRoad) October 1, 2017
That's totally sensible; barrier we've seen is that most players really want to have monsters that stick around be the focus
— Mike Mearls (@mikemearls) October 1, 2017
The necromancer is already the go to ‘summoner’/minion class. What would you do different from it? My personal goal – summoned minions that felt like NPCs, personalities, stick around
— Mike Mearls (@mikemearls) October 1, 2017
As a Dm, combat summoning creates encounter balance issue and combat grind. I suggest summoned creatures use the swarm mechanic and as a whole operate as one single creature. SO a swarm of bats, a swarm of sprites, a horde of zombies etc. all on one initiative , one set of attacks or special abilities like grapple and bite for the zombies.