The interior of the Iron Keep is pretty well guarded by very "Eastern" knights wielding katanas who do a good job in giving me a hard time. An explorer named Magerold is here too, selling wares and talking about a shrine of dragons somewhere as well as Lucatiel who finally joins my party. I also should note this is the first area of the game that I've seen player summon signs, and get my very first co-op cleric named Lee.
The more the merrier!
The three of us make easy work of a smelter demon boss (1st go), which causes my team to disband. Lee waves vigorously as he vanishes. I only realize now that there is no actual method of communication beyond in game gestures and slow to write messages, so I spend a few minutes after the battle to learn and practice the gestures my character knows. In case you are reading this, thank you Lee!
The next area is some type of foundry which really kicks my butt with enemies knocking me into lava or just overwhelming me. Takes awhile before I find an alternate route (hard to see during combat and fire traps) above the gauntlet, defeating Oliver the Collector and finding a switch to turn off all the flame traps in the keep. Then I found the inappropriately dressed Manhunter O'Harrah nearby who accompanied me onto a lake of lava to face this guy...
Didn't Gandalf deal with you?