You know, most people, at first, get a game and want to play the easiest, simplest char. In this case, it's usually regulus, lol. After playing the game and seeing all the ins and outs, I want the most complicated DG... assuming it pays off (QoT = fail). In this case, TB for me.
Ice build is the bees knees for tight knit team games, but in open matches, fire build is the way to go, imho. If you can't work closely with teammates, ice build lacks the damage output for solo'ing a lane.
2 helms + staff of renewal, helped me figure out a few things.
Fireball is by far the best tower killer. You stay out of range, it's relatively cheap for the damage after lvl 2, and has a quick cooldown.
Fire Ring is only useful when an enemy DG is closing in or to help deter or turn the fight when a friendly DG is trying to escape past you. (sometimes I get at least lvl 1 or 2 in freeze, that delay plus the movement speed slow is perfect to help my guys get out. Plus you can drop to the ground from fire to ice instantly, just keep hitting the key and you only lose like .2 secs)
Fire explosion is good in lvl 1 form until later (unless you are swimming in mana). Clears minions quick, but not useful for damage output until the last 2 levels.
Fire Ring + sigil of vitality = enemy runs.
Fire Ring VS not-so-good DA is great. They always run right into it and/or swap with you, putting themselves in the damage area.
If anyone has more tips, please let me know. I'm always looking for ways to optimize ol TB. He's such a versatile DG, but you have to know which build you're taking early on. I've yet to find a good hybrid build. The interrupt is very limited in usefulness. DA, Ere, QoT, Sedna, ETC all have near instant abilities, so you aren't going to purposefully get one on them (I've tried on sedna, but even if you're 100% ready, by time you click and the ability goes through, she's already finished healing). So that leaves you with freeze (very nice!), rain of ice (good AoE, but expensive and not dmg heavy), and slow downs. Slowing the enemy doesn't help much if they're chasing you, vs a fire build speed increase + any speed increasing item is much better.