I have to argue that what your build does, this Ice build does better. You raise interesting points about permafrost vs Fire Aura, I will look into your build with a few play tests and come back with more input. To me it is a pain to switch into frost to get a interupt or stun off (even though it's always worth it) and loose the aura you have in the other tree. Your build will also have a bad lull after level 10 (which many TB builds actually experience) But unlike many other tb builds, your lull will pretty much last the rest of the game. This basically means if you arent winning by level 10, you will have a hard time getting the upper hand with your itemization and skill point placement.

1 Rain of Ice

2 Permafrost

3 Deep Freeze

4 Rain of Ice 2

5 Frost Nova

6 Permafrost 2

7 Rain of Ice 3

8 Perfafrost 3

9 Save

10 Rain of Ice 4 and Frost Nova 2

at 15 you get Frost Nova 3 and the upgrade to Rain of Ice. In between 11 - 14 you can up Deep Freeze to 4 for spike damage

Edit: Fire build is the weakest tree. The spike damage it provides is primarily single target, and is only viable when there is a player for each available lane of creeps (3v3 in cataract) Once 4 players are in the game, only 1 has to have an ability based counter to make fireball completely useless. AoE is what TB is for, to not use this to its fullest is... your hurting your team more than your aura's and fireball can make up for. Even the fire based AoE is just not enough, either of them. Circle of fire doesn't kill giants end game, DG's don't stand in it, you have it centered around your self (small AoE range to). Your spike damage AoE is only good against creeps, even when you max it at 15, it is not enough to counter act heals/bramble shield on multiple demigods. Ice and true-hybrids are the only viable builds with TB. If you are winning with a fire main build, your opponents are just not good enough. Learn to play Ice, all of your future teams will appreciate you much more.

Ice TB is better then Fire TB in all situations, 1v1, 2v2, etc

Disagree.  2v2 and above.... fireball can be a big factor for damage + range.  I get the benefits of ice or mixed, but still go fire ftw.  Might be a fun 1v1 if you are interested (pretty sure you've got the edge on me in 1v1 though, but I'm game). 

ice vs fire, ice would always win..

foreshadowed... we should try a 2v2 (noting my post indicating i didn't think fire v ice would win 1v1).  2v2 though, I think fire has it.  We could have a game to decide

I think a 2v2 match would be fun w u tb ice + another v me tb fire + another. what do you think?

It can be interrupted it is not dps at all.

Also ice will beat fire if he interrupts the fireballs  most times, especially because it's fires only ranged damage.

Fire TB is ok. Ice seems to work better under most circumstances but its not like fire is actually outright bad (the way Sedna Yetis are just terrible). 

fireball is mana efficient and long range. its a fantastic harrassing spell. its also great at finishing runners. it plays out almost identically to Venom Spit in most circumstances. 

circle of fire is much maligned but its very effective as a group support spell on certain maps. it is a bit contextual though, but under the right circumstances its very effective. other times it does almost nothing though so its understandably not too popular. 

fire nova is great at creep clearing and reasonably good at adding burst damage against DG's. its very high mana cost though, which prevents it from really being super strong. 

the fire aura is always underestimated. people tend to forget that it also benefits your team-mates. granting attack and run speed to your allies is very strong. if only they would fix the Fire mode auto-attacks it would be incredibly strong for TB himself as well. 

Why is everyone forgetting the synergy Fire TB gets from his skills.

1) Fire aura enables you to play with no speed item beside Wand of Speed

2) One of the best level 15 skills (IMO), Inspirational Flame enables you to play with a single, cheap helm.

3) Almost all of Fire TB damage comes from abilities, so he doesn't need damage items.

This enables Fire TB to concentrate heavily on HP/Amor without sacrificing anything else.  4 armors is the way I play Fire TB and IMO that is the way it should be played.  It can deliver both burst and sustained damage while being able to take some too.

People belittle CoF too much.  It delivers the damage right where it's needed, around the objective you're fighting for, be it a flag, tower or a Demigod.  Sure people move out of it, but you get few potshots while they do, and you still end up clreaing up the reinforcements.

True, AA bug is a big problem, but you can work around it early game by switching to ice, and late game you just have to learn to live without it (untill it's fixed that is).

The biggest problem I see with Fire TBs is that everyone seems to get Fire Nova at level 5.  While clearing a creep wave in 0,5s is nice, it's utter waste.   Nova justs costs too much to be used that early.

The problem with circle of flame is that the opponent gets to decide how it will effect them.  If they can take the damage, they can decide to enter or stay in the circle, if they can't, they move away.

And I think the mana boost for inspirational flame is actually moot in many cases.  By that point you had to use whatever mana regen you used, and only at the very end of the game would you be able to seel perhaps one mana source to buy something else. It isn't like the inspirational flame effect was a growing cumulative thing. I'd rather use more mana efficient spells, than try to get more sources of mana, for TB especially.

Not to mention that interrupting with Deep Freeze also puts a cooldown increase on it.

In my experience a Fire TB can beat an Ice TB if Fire has Staff of Renewal and Ice doesn't, but that's only in a 1v1.  In larger battles Ice abilities become much more useful.

zech is right. This tooltip needs to be edited.

Oh yeah forgot about that....they should've made it not remove the extra time when it wears off; most stuff's cooldown is longer than 5,6,7 seconds anyway so it doesn't really do crap.

Shouldn't it be adding ~9 seconds to a 7-second cooldown though (ignoring that it goes away after it wears off)?  IIRC level 1 says it "increases target's cooldown times by 130%" which implies it's adding the full 100% before the 30%.  If it really does add 130% and not just 30% then using it just prior to when the cooldown ends should bring it back up to 9, effectively preventing it from being used for the 5-second duration of the debuff.