So, what's the general consensus on teleporting into other hazards? Say into a spot of a known trap that the enemy will trigger if put there? I ask because my avanger used this on a kobold to put him into his own pit trap once.
I guess this issue is the same as the ledge one: the DM shouldn't make any other hazards that are instant kills either.
As per page 44 of the DMG, a creature is entitled to a saving throw if you use forced movement to put it into Hindering Terrain.
Hindering terrain is defined on page 61 of DMG as "Hindering terrain prevents movement (or severely punishes it) or damages creatures that enter it, but allows line of sight." with the examples "Pits, deep water, lava, fire."
You are
not entitled to a saving throw if you are brought into a dangerous situation that is
not due to hindering terrain, such as within striking range a dangerous creature.
Now, is a trap considered hindering terrain, or is it just another dangerous situation, such as the above creature? In the Encounter chapter of the DMG, traps seem to be closer to monsters than to terrain, but I guess that it comes down to individual DM judgement call in absence of anything clearcut.
If traps are included as hindering terrain, another important aspect is if the danger has to be known. If you slide creatures off a ledge with the slidees not knowing about their imminent fall (due to blindness, illusions, unconsciousness etc), are they still entitled to saves? If you slide someone into a trap they dont know about, what happens?
I would claim that this too comes down to individual case-by-case DM judgement call.