I was thinking about 4e’s encounter design, and something hit me that may well be applicable in several sorts of games.
In 4e, the base assumption is that you’ll have one foe per character. This is modified by a bunch of things – minions count as multiple foes, elite creatures count as two, and things like that. I find this somewhat cumbersome in that you often want to have a single monster in an encounter. In particular, I was thinking about my abortive WoAdWriMo attempt last year and the difficulties involved in converting it to 4e. One of the early (optional) encounters was with a gibbering mouther. Now, adding in another beastie to this encounter just wouldn’t make a whole lot of sense. The mouther was notable for being alone in the area it inhabited.
Then I had an epiphany that will likely cause most of you who read to say, “duh.” I realized that I could have a big mouther and several smaller mouthery-things in the same area, but describe them all as a single creature that had spread across an entire area. The amorphous nature of the gibbering mouther makes this particularly easy. PCs could kill a mini-mouther and it could simply be described as severing a particularly long psuedopod or whatnot.
The cool thing is that I then said (to myself. and my cat.) “Hey. This could solve the hydra problem.” The hydra is notoriously difficult to model in rpgs – particularly if you want to do the cut-off-a-head-and-two-others-grow-to-take-its-place thing. The solution? Treat each head as a separate monster. In 4e, give each hydra-head the power to split when first bloodied (like the Ocher Jelly) unless fire is applied.