i'm sure you're aware of the various monster packs available at http://www.hazelwhorley.com/ini/monsters.html.
More isn't always better. even tho the current config got more monsters. I'd rather have a mini-boss wave of human-sized lucifers or something else even, than 300 monsters that take forever to kill off.
with a small handfull (say a dozen) minibosses, everyone can get involved. the noobs won't die immediately and it'll take all the resources of the higher players to bring it down.
as an adren master, lucifer is usually pretty tuff for me. Most of the time i run around with globe on feeding adren with mine/flak and i can run whole waves globed. with lucifer, that's not possible... it's one guy, he jumps around like a rabbit, and he's always running, so you're never really safe. And since he's constantly moving around, i have a hard time targeting to keep my energy up. and even if he does settle down, his various defenses tend to keep me from max gain. our only real hope is that he gets into a position where we can see him, but he can't see us, then we kill him with the deadly foot wound.
therefore, i think that the odd miniboss would help keep the game challenging for highlevel players without arbitrarily excluding lowlevels.
a miniboss should have a mish-mash of the following:
1) significant Damage Reduction
this will REALLY reduce globing and reduce the damage from the potential 15 incoming deemers and painters.
2) an immunity
chrome skaarj are energy immune (link, lightning, shock). queen/warrior shield is energy immune. but there's nothing that is ordinance immune (mines, rocket, mini/ar, flak, sniper) and imo it should be considered.
3) fast
lucifer's movement is an example of the fast i'm talkin about. if he picks a target in the same area and decides to go kick ass, he's all over it right now. a miniboss doesn't need to move that god-awful fast, but a fast monster will last longer.
4) smart
this might be tuffest part. lucifer's head is the only thing that detects players. therefore if he's getting shot but doesn't see anyone, he just stands there like a pillar of salt. if he's NOT getting shot and doesn't see anyone, he idles and walks around. our minibosses should know when they're being shot and should at the very least move away, but optimally try to find the shooter. Maybe scripting in that if they're getting shot AND they can't see any shooter at all to jump away from the shot. this would disrupt everything and force players to actually play rather than try to kill his ankle.
5) very strong.
and i mean in health. why not have 8 guys with 7k hp each on wave 12?
6) unique weapon.
while the warlord and doom-spider-broad shoot different projectiles, they're essentially both the same logic. rockets.
How about a miniboss queen that throws 6 pupae that attack with poison? Ok ok that might be a bit much but what about a queen that attacks with poison? how about a warlord that shoots exploding barrels? how about a tide of a few hundred pupae that attack with .25 sec freezing or null? how about a giant nali-cow with 25k health that is immune to both energy and ordinance (leaving only supers and shieldgun) and has a charge attack of knockback +20?
now here's the thing: of the shit i mentioned right there in that para, it can either be built using available resources (the above link has a great tute), or is actually available.
to the naysayer that decries "it's not very realistic for a warlord to . . . " uh . . . yeah right. you're playing this for realism?
so the warlord mentioned there would demand a change in tactics. the giant nali cow would be insane as it turns, picking new targets and knocking guys out of the way.
my point here with a miniboss is to give some challenge without being overdone to the lower level players. the interesting byproduct is that it'll break up the Fire And Foreget mindset of most inv play and change up the regular game a bit.