Creature "waves"

 

Ok here is a quick way I devised to have "waves" of creatures.
Pick a die - like 1d6, 1d8, 1d20
EDIT: For Demon City - just do a C10 throw!

start with one creature
the players encounter it - and if it is killed - have each of them roll the die you chose - if they roll above the number of creatures they just killed - add one creature and keep going

so
One creature
fight
if it is killed
all the player characters roll the chosen die
if they roll above the amount of creatures killed
add one and that many are encountered

so
1 creatures 
fight
fail roll =

2 creatures
fight
fail roll=

3 creatures
fight
fail roll=

4 creatures
fight
fail roll=

5 creatures
fight
fail roll=

6 creatures
fight
fail roll=

...

This works well for:
Giant rats, Giant Crabs, giant Bats, Giant spiders, kobolds, goblins, mudmen, skeletons animating, Giant millipedes, a creature's tentacles, cultists, etc
nests, or something where a new thing emerges over time as they fight.

good things to do:
as each enters - have them enter a diff way - or the same way
so - one cultist walks into room
gets killed
the players fail

then two more try to come through the door - 

then three
then four
until the players succeed

OR

have one cultist enter through the door
then two from behind
then three through a secret door
then one from each doorway, four in total
then...


rats scurry out of holes and cracks and fissures and piles of rubble
giant crabs emerge out of sand or surf or around the edges of rocks
bats swoop in from high ceiling or through doorways, or out of a nest
giant spiders drop from ceiling or scuttle from webs in corners
kobolds hide behind pillars and crates and rubble and run through passages
goblins wander in through doors - or on little hot air balloons - or raptor mounts or whatever
mudmen come out of mud
skeletons come out of graves, tombs, piles of bones, the soil, or walk in through doorways
giant millipedes crawl through cracks, drop from ceilings, crawl along walls, creep under doors
a creature's tentacles emerge from water or through doorway
cultists emerge through doors and passages and stuff


ok thanks