Rethinking the use of the Umber Hulk after all the comments saying it'll be too easy a challenge for the party. I'm hoping to do very little tweaking to the monster I use as this is more an encounter for flavor and narrative than for a satisfying combat encounter.
Looking to use a higher level monster then perhaps. One that has higher defenses and higher average damage, so while he may not be a full challenge for a party of 5 heroes, the math will make him harder to hit and more deadly for a brief skirmish.
The Steel Gorgon is another iconic monster that would work well. As a lvl 15 elite, we're already talking about a harder fight. Glancing at defenses, we're looking at roughly a 15+ to hit, possibly more, and even if I started the Gorgon out bloodied (for narrative effect), they'd have to burn 151 hp to bring him down.
Damage-wise, this guy could easily bring down the party's ranger with 3 average damage hits, or bloody her in one max damage.
Even if the heroes beat him down, it should be pretty draining. I've been looking forward to an "oh sh*t" moment with them, as most encounters I've thrown at them have been either really well balanced, or a cake walk. Even if it's a grossly over-leveled monster, I'm happy with that kind of effect.
Trit