Many spells that inflict AOE damage over the course of more than one turn describe that the subject takes the damage when it enters the area or starts its turn there.
I quote for example the PHB spell cloud of daggers:
A creature takes 4d4 slashing damage when it enters the spell's area for the first time on a turn or starts its turn there. (PHB, p. 222)
It seems pretty clear, but I had some doubts in a peculiar situation. We were fighting some underground worms and our party's sorceress readied the cloud of daggers spell to target the first enemy that would have appeared. A worm jumped out of the ground and she cast the spell, but she fell unconscious right away (the worm attacked her) and so the monster didn't actually start any turn in the area nor moved in, so the master negated the damage.
Rationally it makes little sense to me that for one turn it stayed in the cloud and still didn't take damage. Did I misunderstand how the events took place?
My questions are:
- Do you know a rule/official tweet that explains more deeply this kind of situation?
- How could the situation be described so that it would have made sense?