Huh. Interesting concept.

A potential problem is when PC powers are only supposed to affect a specific number of targets. A warlock can lift one creature off the ground with storm countess's kiss, but if that one "creature" is a horde, it leaves you wondering why the same warlock can't do that to other creatures in large numbers right next to each other. Without trying to attain realism -- because, frankly, realism should take a back seat to good play in 4e -- it still might be best to change the way the horde interacts with that kind of power.

The creatures in hordes are individually kinda wimpy, so they shouldn't have better saves than a standalone.

Here's a suggestion that helps with both those issues but requires extra rolling. The horde takes a -2 or +0 to saves instead of the usual +2. They roll a save against each damage instance or effect as it happens, unless it could affect each of the component creatures individually (like many bursts/blasts, the hunter ranger's rapid shot, or maybe a multitarget melee power with a reach weapon). Saving this way against damage halves it, and saving against an effect negates it.

Quote Originally Posted by Arcacius View Post
Change Base Creatures Attacks as follows
Melee X -> Close Burst X
Ranged X -> Area 1 Burst within X
Area X Burst within Y -> Area X+1 Burst within Y
Close Blast X -> Close Blast X+2
If you choose to let the horde overlap space with other creatures, you'd also want to specify that their new close burst powers include their own space.

Oh, hmm, what about OAs? Maybe the horde should retain MBAs as well as getting a non-basic-attack close burst, so they still get a swipe at anyone walking by but don't get to swipe at everyone for one person walking by.