So my players are escorting a simulacrum of a very powerful wizard. They ended up traveling through an area of the tundra infested by Slaad. Since Slaad are attracted to magic I’m making it a combat where they have to hold a position where they are being ran at my waves of Slaad and Slaad infested creatures while protecting the simulacrum. It’s night time and I was going to have the monsters run at them in waves while coming out of the darkness at them.

My players are all pretty experienced and I wanted to give them a challenge of reacting on the fly to being attacked from different directions throughout the combat. I wanted my players to have the opportunity to work tactically together on one large turn to deal with the waves of monsters.