Right, for anyone thats attempting Hodir Hard mode and are having Tank Threat trouble, this is a neat trick that might help you out.
Required Reagents :
A Tank that can Taunt (obviously)
A Mage
Right what you need to do is get your best geared Mage to get as much of the fight buffs as he can get,
Pop Mirror Image, and nuke his ass off.
When Mirror image wears off the Mage will get all the threat he just made instantly, resulting in an overaggro.
Now you want your MT to Taunt and your Mage to Invisibility.
If you did it right and your mage is properly geared to do masses of threat,
You'll get the result we get which is the Tank having loads of threat.
There you go, you successfully boosted your Tanks threat by loads.
Gogo Hodir Hard modes !
!P.S. This Will Probably Work On Every(Or Most) Tauntable Boss(es)!