Well. You've got Tower and Martyr. Those two need to be in for sure.
Septimus is pretty solid too - he hits hard and extends debuffs.
I'd suggest consulting Roschard the Tower (deadwoodjedi.com) - the teams there should be a good start.
I see a tower and skullcrusher, they are the bones of a unkillable comp, doompriest or someone with a three turn CD block debuffs need to be on the team for it to work. Then you just add in a def down champ and a poison champion and two or three key unm and one or two key nightmare.
Speeds are very important to pull this off so it depends on the gear you have on your account pretty heavily.
My current set up with this comp is as follows
Tower 248 speed - blocks aoes
Fayne 186 speed - weaken/defense down
Occult brawler 181 speed - posions
Brogni 173 speed - block debuffs
Valk 171 speed - counter attack and stun target
The biggest down side to this comp is affinities as it really only works on void and magic, can do others with this some manual finesse but not all the way to turn 50.
The benefits is that vs void it's a easy two key unm and one key nightmare. The setup is minimal and is full auto after one turn. If you have a block debuffs champ and want to try out this comp I would suggest looking at the deadwoodjedi.com website as speeds will differ from what I listed depending on the champs you use.
I use tower fully booked to block
lost bride to revive and heal Also does block buffs fully booked as well
Elenaril for hp burn and posion
i use long beard for weaken
and skullcrusher for counter attack he also has an unkillable which is good for them final attacks
Siphi block debuffs is a 4 turn CD booked, you need a 3 turn for what I was talking about, and you wouldn't need rez as no one ever dies.
Do you have a grizzled jarl or brogni?