I was re-reading the description for Persistent.
So before I get there I will look at Incendiary as they are similar effects. Incendiary sets the target ablaze for a number of rounds equal to the effects rolled on the damage. At the end of the targets turn they suffer an additional Xcd damage, effects increase the number of rounds the target is set ablaze, but the damage is only applied once per turn.
Persistent says the target suffers Xcd at the start of each subsequent turn. This lasts for as many rounds as effects are rolled and new effects rolled add additional rounds. I haven’t used persistent a whole lot, if ever, but wanted some feedback on how I am interpreting that rule, see below, where I am inflicting the persistent damage multiple times in a round.
So. We have our heroic adventurer bob fighting against 3 scorpions.
Bob attacks and kills the first scorpion.
The second scorpion hits Bob and does Persistent 1, with 2 effects rolled, so it lasts for 2 rounds.
The this scorpion attacks, this is the start of a subsequent turn. Bob takes 1 more damage from the persistent. This scorpion misses.
Bob attacks, the start of a subsequent turn, bob takes another damage, but an effect is rolled and so the persistent duration increases by a round. Bob kills the next scorpion
Final Scorpion attacks and again this is the start of a subsequent turn and so Bob takes another 1cd of damage from the persistent effect.