|Russ Taylor Contributor, RPG Superstar 2008 Top 6|
|Jeremy Mac Donald|
I'd say trap, but when the rot grubs actually infect the host treat it as a disease.
Ongoing damage outside of combat is possible in 4e but not well supported.
Of course, if I remember correctly (not likely), I thought the grubs infected the host upon contact with whatever they infested. If you still want that direct infection without a save (a hallmark of old school adventures) then go with a pure disease.
Allow the disease to be healed normally but also allow the application of fire to do its work.
Initial infection should remove at least one healing surge. Afterwards simply reduce hit points as you move down the disease track. Make them unrecoverable until the character improves. Perhaps a character could lose them in 1/4 increments.
The only problem with going the disease route is the length of time the infection spreads. A character normally only gets an Endurance check after an extended rest and thus that determines the speed of infection. But if you don't mind that then it won't be a problem.
I am adapting The Sinister Secret of Saltmarsh to 4E and I am trying to stat up some Rot Grubs for a 1st level party.
How should I go about it? Make is a Disease? A Swarm?
A trap that has its EFFECT as a disease/poison from the infestation. From there, it depends on how deadly you want it. The encounter lasts until the grub is healed away, killed in some other way (burning it off and out?, physical HP of its own), or the host is dead, in which case it's a trap AGAIN.
Each round in the encounter, have it do X amount of damage. If 'combat is over', then fall back on the 15 seconds per 'combat turn' guideline to handle damage and everything.