Demons, Silence and Teleport.

[MonsterEnvy]

Just inform you all the creatures that have innate spellcasting don't require material components.

 

[TheGogmagog]

Forcecage can stop it, if the demon fails its Cha save.

You could have custom spells or psionic abilities like Dimensional Lock that would stop teleport, too, even if it's not from a spell.

Antimagic Shell would also prevent teleportation.

I believe Mordenkainen's Private Sanctum would prevent teleportation but I'd have to double-check the spell description.

Magic circle also works., though the minute long casting makes it impractical.

 

[dave2008]

Just inform you all the creatures that have innate spellcasting don't require material components.

But some (actually most) of them do require other components

 

[MechaTarrasque]

Just remember that teleport takes the marilith's action, so she really can't do anything else, except move and parry on that turn. A monster who teleports all the time in 5e is basically a harmless nuisance (unless you are trying to sneak in or out of someplace, and the marilith seeing you and teleporting means 1,000 demons will be pouring through the door the next round).

 

[Croesus]

Just remember that teleport takes the marilith's action, so she really can't do anything else, except move and parry on that turn. A monster who teleports all the time in 5e is basically a harmless nuisance (unless you are trying to sneak in or out of someplace, and the marilith seeing you and teleporting means 1,000 demons will be pouring through the door the next round).

Yeah, I had to read the monster write-up multiple times to be sure that was the intent. Teleporting does not replace movement, it replaces the action. As you say, teleporting is pretty useless in most situations. Oh well...

 

[MechaTarrasque]

Well, 5e is about cutting down the combos (both for monster and PC). I think the only way to consistently "pull a Nightcrawler" is with misty step, and that is one cast per use, which means about the time you can do it a lot during a fight, you have better things to do....

Hmm....I may have to figure out an epic monster for dave2008's thread that gets misty step as an at-will spell, since misty step (bonus action) plus multiattack (action) could get pretty ugly since that doesn't show up in the game very much anymore.....

 

[dave2008]

Hmm....I may have to figure out an epic monster for dave2008's thread that gets misty step as an at-will spell, since misty step (bonus action) plus multiattack (action) could get pretty ugly since that doesn't show up in the game very much anymore.....

I like that idea