The duration of this spell is 1 round.
Does that mean that someone who is on open ground and falls into a fissure has one round to escape? Or is the idea that anyone who fails both saves just dies? Reading the spell it says that people on the ground can't move or attack, but that spells can be cast with a successful concentration check. Does that mean that you can't climb out of a fissure, but if you can cast teleport or something you might get away?
The duration of this spell is 1 round.
Does that mean that someone who is on open ground and falls into a fissure has one round to escape? Or is the idea that anyone who fails both saves just dies? Reading the spell it says that people on the ground can't move or attack, but that spells can be cast with a successful concentration check. Does that mean that you can't climb out of a fissure, but if you can cast teleport or something you might get away?
As written that is what it seems to say, except any creature in the area only needs to fail the DC 20 save to be caught in the fissure.
Personally I'd prob allow a climb check for a 10ft deep chasm at a DC of 20 (15 for rough natural surface + 5 for it still being crumbling). The only downside is that even if you make the check you still would need a movement of 40ft/round or more to make it out in 1 round. A standing start high jump DC of 80 should also make it out.
The duration of this spell is 1 round.
Does that mean that someone who is on open ground and falls into a fissure has one round to escape? Or is the idea that anyone who fails both saves just dies? Reading the spell it says that people on the ground can't move or attack, but that spells can be cast with a successful concentration check. Does that mean that you can't climb out of a fissure, but if you can cast teleport or something you might get away?
That's what it looks like to me. Once you fail the second save and fall into the fissure, you're tumbling down into the center of the earth with no discernible bottom or sides, since these are big fissures capable of swallowing the Tarrasque (note the lack of limitations on size).
However, you can rescue yourself at the last minute with a spell or some variety of magic item activation, or possibly with something as mundane as someone throwing you a rope and hauling you out before the fissure grinds shut.
Teleport would certainly save you, but so would simpler spells such as Dimension Door, Levitate, Fly and good old Rope Trick.