A Tank, or as I like to call it, and Aggro-grabber.
I'm considering making a loadout later in game for this kind of class, here's what stuff I'm looking at
Armor
Mecurial or Ironmight Plate
Merrcurial-Speed to outrun monsters
Ironmight-Defense to tank monsters
Weapons
Argent/Sentenza-For grabbing aggro from monsters.
Graviton/Electron-For trapping enemies behind you
Shivermist-Trapping enemies(maybe another status bomb for grabbing aggro)
Weapons in case of surrounded (with plate armor)
Levithan
Nitronome(or other blast bomb)
Shields
Any Shield or Ironmight Plate
Basically the strategy varies from two types: Kiting or blocking
Kiting-Grab as much aggro as you can and run around avoiding attacks but allowing your teamates to attack (Mercurial)
Blocking-Get right in the action aggroing monster and tanking with your shield and armor while teamates attack from behind (Ironmight)
Do you guys think it would be a valid class to use?
Mercurial's speed boost is relatively minor. I doubt you would outrun anything you wouldnt normally outrun.
Ironmight doesnt tank damage. It is as effective as any other 5* armor is absorbing damage(which isnt much in T3)
The weapons are decent but monsters aggro on the person that does the most damage so you would quickly lose aggro as your teammates start attacking.
Also if you had everything aggroed on you your shield would break pretty quickly.