Hello folks, I just wanted to run some of the rules regarding Thunderwave past you all. If a player or monster fails their initial saving throw and the knockback sends them off a cliff, do they have a saving throw chance to grab the edge of the cliff? I thought I read somewhere that they do, but can't find it now.

Thanks

Up to DM. But there are no rules for it as far I can recall. They are pushed the distance by the spell. If they are now in the air with nothing below them - they fall. 

Many thanks. In this case I'm the DM, so unless they'd land on the actual edge, I'll have them just fall. On the edge I'd say a DC15 dexterity would make sense. 

They should definitely get a save to catch the edge.  It's only a first level spell, should not do massive damage which is possible.

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This is absolutely up to the DM to decide. There are no rules specifically about if a player is knocked/thrown/pushed/etc off of a cliff (as far as I know). 

However there are a few things to consider, if you are the DM:

• How will the players feel about this? If it is a really cool moment near the end of a tough fight, let the player push the NPC over without a saving throw so they can feel like they did something clever, that they had a big win. These moments can be very important for players, especially newer players.
• What kind monster is it? If it is a simple worg or random goblin, maybe let them just fall. If they are a Named Villain or BBEG, some important antagonist, maybe have them attempt a save. This will solidify their power/importance and make them feel like a "tougher" opponent. Also of course take physiology into consideration. A humanoid can try to catch the edge of a cliff, but something like an Allosaurus would probably be unlikely to catch itself. 
• If it is a player character, let them attempt a save. "You got pushed off the cliff, you instantly die with nothing you can do" is a really unsatisfying ending to a PC's life. Could they have made smarter choices? For sure, standing by a cliff is a bad idea. FAFO. But also we want the players to have fun, feel like they have agency, and feel powerful (depending on your table, I guess). Letting the players save in a situation like this is usually a very good idea and doesn't break any kind of game balance IMO.

Quote from MaximusArael020 >>

This is absolutely up to the DM to decide. There are no rules specifically about if a player is knocked/thrown/pushed/etc off of a cliff (as far as I know). 

However there are a few things to consider, if you are the DM:

• How will the players feel about this? If it is a really cool moment near the end of a tough fight, let the player push the NPC over without a saving throw so they can feel like they did something clever, that they had a big win. These moments can be very important for players, especially newer players.
• What kind monster is it? If it is a simple worg or random goblin, maybe let them just fall. If they are a Named Villain or BBEG, some important antagonist, maybe have them attempt a save. This will solidify their power/importance and make them feel like a "tougher" opponent. Also of course take physiology into consideration. A humanoid can try to catch the edge of a cliff, but something like an Allosaurus would probably be unlikely to catch itself. 
• If it is a player character, let them attempt a save. "You got pushed off the cliff, you instantly die with nothing you can do" is a really unsatisfying ending to a PC's life. Could they have made smarter choices? For sure, standing by a cliff is a bad idea. FAFO. But also we want the players to have fun, feel like they have agency, and feel powerful (depending on your table, I guess). Letting the players save in a situation like this is usually a very good idea and doesn't break any kind of game balance IMO.

 Thanks, very good points. I'll take you advice. 

The most important part is to remain consistent. If you let the PCs have a save, the monsters should get one too. If you don't let the monsters have one, the PCs shouldn't get one.

Also be open with the players attempting to use forced movement. Players making distinct choices to build characters trying to make use of forced movement which are immediately needed defeats some of the purpose for that build in the first place.

I played a built and played a monk using the crusher feat in a campaign once. The DM built several encounters in a cave that had pits and chasms around. After pushing a creature over the edge the creature immediately passed a save and didn’t fall. I immediately changed play styles with that character and then ended up never playing it again.