Ice patch only affects 5 at a time and higher level mobs can run off the patch.
Burn also only affects 5 at a time and causes a fear (run away) affect.
Any tank with fire melee is better offensively than a fire/ice tank, even with the new improved Frozen Aura.
fire/fire is good for solo or small teams. (my fire/ice is for small teams, I use my stone/fire or ice/stone for large teams)
YMMV---IMO
Ice Ember
Mostly what Ice Ember said (fire/fire better than fire/ice), but! fire/ice is VERY viable.
But a question for you: Do you use tough? CJ+weave? IO sets?
Define 'viable'? Are you looking for a team tank (max survivability, damage isnt important), overall tank, or most offensive tank?
Did you take fireball?
Here is a strategy I have used: use burn last. I like to pull to a cornerDrop ice patch (it helps greatly in survivability), hit fe+bu (or just one), frozen aura (FE is on a short timer for non fire damage), pop out of the ice patch just outside of mobs so I can line them all up for frost, fireball (if your 50), then burn (if your in a corner, and you hit burn, they will try to run away but they are in a corner. Some will go to the sides, but more will stay) . Have burning aura running all the time. I used the fire powers last, as FE boost is still valid, and burn causes them to run, making frost less effective (frost is a short cone). I hit more with frozen aura, so I like to lead off with that.
They wont run from frozen aura, frost, fireball, burning aura, but they do from burn *rolls eyes*. If your teamed with a controller, they can immob/hold and you can burn away.
Also, the '5' limit is mostly valid. It doesn only affect 5 at any one time, but I have had 10 foes on my ice patch and burn patch. This means, the KD effect of ice patch will affect 5 foes at a time (so when one is getting up, it may apply KD to another), same with burn. Also, here is how it should work: burn rolls a to hit against 10 foes. Say it hits 6, but is set to 5 (the max). But if you had 5 foes, and it hits 4, only 4 take damage. And each tick is a new 'to hit' roll.
50 Tanks: Invul/ss, Fire/ice/fire, Ice/em, Stone/fire
WP/Stone, dark/dark, shld/mace
50 Other: WS, SS/dark/sc brute, BS/Regen/WM scrpr, fire/fire/force blaster, rad/kin corr, mind/rad ctrl, ill/storm cntrl
Is fire/ice a viable solo class to 50 anymore? I logged in my old tanker yesterday(i have been out of the game for years) and it seem they changed the ice patch becuase Mobs were falling then getting up and running off it. They used to stay on it while I taunted them but they seem to be able to run off it now.