There are bosses. But they are'nt labeled "boss here", and unlike hackemslashes,
EU bosses don't necessarily give good loot BUT they can.
If you research
eu history, you can learn about cool mobs and when they spawned/what the dropped:
Eomons
Warlocks
High Gen. Segs
Atrox Elite/Slayer/Marauder
Argonaut Elite Series
Migration Event - Elite Exas and a whole heap of high maturity mobs that usually go unseen.
High Level Umbranoid - scary because the have armor. (more coming soon)
But there are everyday bosses you might not realise:
Atrax Stalker - over 10 times harder than the Prowler
Aurli Queen - Seen more rare than Warlocks.
Araneatrox Stalker - If you kiled 100 of these things and didn't get something nice, you'd have to be the unluckiest avatar in all
EU
Hogglo Old Alpha and Above - harder than Spider Stalkers. SPiders Miss. Hogglo don't.
Beacon Missions - if this isn't 'bosslike' enough for you.... what is? Done a 35 hard mission yet?
I know what you mean, you want a hackemslash mob-boss appearing. But
EU hunting is more about what you CAN hunt, rather than what is beyond your abilities. If everyone found out the atrax stalker was dropping a lot of nice stuff, they'd all hunt it.
MA have learned from events in the past that lag kills everyone's fun, and have stated they will avoid the kind of events that involve lots of green dots and lots of red dots.