You probably don't want to use a Brogni.
That will make him unviable for other content due to low speed and his shield mechanics may mess it up.
Which composition are you doing?
The Slow Skullcrusher, Tower is definitely the easiest. Deadwoodjedi.com has a link to a reddit post that is very helpful.
Do you have a Doompriest, or anyone with a skill that places Block Debuffs on all allies on a 3-turn cooldown?
That is what is required. Roshcard's A3 needs to be booked. Skullcrusher's A2 needs to be booked as well, and if you are using a Block Debuffs champion, you need that skill to be booked.
Speeds-
Tower 245
Skullcrusher 174
dps 178
dps 177
Then if you are using a Doompriest, the speed is 186, but a block debuffs champion needs to be 173. The faster dps would be the one with decrease defense or weaken.
Skullcrusher needs the lowest HP of everyone. Avoid HP% and HP stats. He also needs a way to earn back HP. That means youll need the Lifedrinker and Warmaster masteries together.
It should work fine on Void NM and UNM.
For Spirit, Doompriest is required. You cannot use a block debuffs champion.
It should work fine on UNM with the same dps as Void. I do sometimes see issues with Spirit on NM. It has to do with the Decrease Speed debuff. I think it has to do with whether the clan boss lands it or not.
For Magic, you can't use Skullcrusher. Youll need a Gnarlhorn instead. The speed is the same and his A3 needs to be booked. His A2 also needs to be booked because sometimes hell prioiritize that over his A3. Once we get AI preferences, the A2 could just be turned off though.
It should work fine with the same dps as Void on NM and UNM.
For Force, youll need a block debuffs champion. You cant use Doompriest. I recommend not running Magic dps because it becomes more difficult to work with stun targets. I run my Tower and Grizzled Jarl (my block debuffs champion) in Immortal to make sure they have more HP than Skullcrusher.
Otherwise, it should work fine on Force UNM. It doesnt work on Force NM.
As I said, there is a guide link to Reddit where a guide is located. Check that out because it may answer some more of your questions.