Our invasions also tend to have "themes". I remember the one (the 2nd?) invasion that had a bit of a silly theme and among other things we had an army of 20,000 frogs somewhere in there.
That was the first one. Still my favorite. I also remember vampire armies that supposedly enlarged their army by battles (don't know if that's true since I never fought them). What I liked so much about it is indeed the diversity in invaders and secondly that those invaders were being lead by heroes that could be killed. Nothing more rewarding than killing some bad-ass invader lord.
EDIT: The second one was when monster/undead hordes first started appearing across the continents I think, and they were HUGE on BT.
