Torch Bearer can be best described as an undead elemental mage. Those who can't get Dungeons and Dragons out of their heads would probably call him a Lich.
TB has two different forms he can freely switch: Fire and Ice. Each form offers him three different attack skills, with Fire focused on dealing massive amounts of damage and Ice focused on freezing, slowing and dealing massive amounts of damage. Note that no skills focus explicitly on keeping you alive.
Like with all demigods there are various ways to play an effective Torch Bearer. Most obvious are the pure fire/ice builds. Pure forms have the obvious benefit of not overloading your brain with the difficult task (pressing the key '4') of having to switch between forms. Skipping one elemental entirely also frees up skill points for use in Enhanced Attributes, improving your auto fight abilities and staying power. And to be fair: Switching forms costs time. Time in which you are not killing anything, so there are valide arguments for staying in one form. Hybrids however offer you the benefit of flexibility in terms of skills available and the highest burst damage possible.
The most distinguishing attribute of Torch Bearer is his wide assortment of area damage skills, making him the best creep farmer and bane of generals. Another standalone feature is the amount of energy TB has, as well as his mana regeneration rate, which both are the highest in the game.
In this guide I want to highlight the benefits of playing a hybrid, which apart from being very strong also produces more pretty colors than pure builds.
Groundworks (Level 1-10)
The following skillpoint distribution is what I consider the bare minimum of what a hybrid Torch Bearer needs. You can decide midgame in which direction your TB goes after this.
The order in which skills are taken are entirely up to preference, but it's most effective if you make one skill your priority and level it up no matter what. My personal preference is starting with Circle of Fire 1, then priority picks of Rain of Ice. Frost Nova takes precedence to Circle of Fire but Rain of Ice comes first.
Rain of Ice 4
This skill is the only range AoE damage skill in the game (excluding Regulus mines). It deals 800 damage in a wide are and can be fired from a 20 yard range, which is well outside of any regular attack range. It also slows attack speed by 40% for 10 seconds, cutting enemy melee damage nearly in half. This is invaluable, especially since TB is so squishy.
Circle of Fire 4 + Inspirational Flame
For the price of 800 mana you get a 1500 damage large area effect. Nothing in the game beats that. The only drawback is that it deals the damage over a span of 10 seconds and you can easily defend against it by stepping out of the circle. Creeps, however, don't. They happily waltz in and get fried to a crisp while the more cautions demigods stand outside the cirlce and get pelted by fireballs, Ice Rain and your ranged auto attacks. Circle of Fire is as much a psycholigical area denial spell as it is a siege breaker. Plant it next to fixed defenses or Rooks tower farm, withdraw and watch the buildings crumble. And gaining extra mana through Inspirational Flame ain't wrong either.
And the most useful aspect: Circle of Fire is stationary. You can slap it down in the middle of a lane and walk over to another lane or a flag located just outside the lane. That way you can gain ground and experience at twice the speed.
Frost Nova 1
Completely freeze your enemies in a large area around yourself to immobility for 6 seconds, including buildings. Demigods are affected considerably less - just one second. They do suffer from a 10% movement penalty for 5 seconds, however, making this a great getaway spell. Or a great siege spell. Enter the range of the enemies towers, freeze them, switch to fire and cast Circle of Fire. Use the rest of the frozen time to pound the towers without getting shot at. Also use the time to get out of range of said towers.
Mid- to Endgame (Level 11-20)
Depending on circumstances and personal preferences you can choose how to go on from here.
The skills listed here are taken in addition to the skills covered in the groundworks section. They whole point of having a common base skill distribution is the tactical flexibility of developing your Demigod depending on the tides of battle. Although in TB's case it all amounts to dealing direct damage quickly.
Variant 1: Infernal Crysis
Your primary goal is to kill other Demigods and you don't want to wait for them die of old age. Go this path if you wish to radically enhance your burst damage to a single target, leaving burning ice in your wake. You use your Ice spells to stack debuffs on your victim and kindly taking them away again, dealing an unholy amount of cold damage as a side effect. Finish off the limping fleeing wreck with the same well placed epic fireball you used to get his attention in the first place and end discussions about how hybrid TBs suck.
In itself this debuff is moderately useful: Reducing health/mana regeneration by 75% for 10 seconds ? Well, in case of Sedna this may result in 750 health not regenerated but this skill doesn't carry the same horror as, say, losing 750 health in one blow. In combination with Deep Freeze it comes close, though, since it can be consumed for an additional 425 points of damage.
Deep Freeze 4
Interrupts enemy skills, increases cooldown by 220% for 7 seconds on the highest level and consumes the debuffs added through Frost Nova, Ice Rain and Biting Chill for 325 points of damage each. What's not to like ?
Shoots a great ball of fire for 1050 points of damage at 20 yards range. Actually even farther, because once you started casting the projectile will hit even if the fleeing victim already moved out of your range. Low cooldown time of 7 seconds, which makes it both a good starter and perfect finisher.
Fire and Ice
Increase fireball damage by 300 and increase Deep Freeze damage by adding 100 damage to each consumed debuff, usually meaning 300 extra damage, too. This is a subtle hint to play a hybrid, by the way.
In a time where you can afford the high mana costs (i.e. endgame), the battle sequence might look like this:
Fireball->Circle of Fire->#->Rain of Ice->Frost Nova->Deep Freeze->#->Fireball
1350 -> ~1500 ->#-> 800 -> --- -> 1275 ->#-> 1350 = 6275 damage
540 -> 700 ->#-> 1100 -> 750 -> 725 ->#-> 540 = 4355 mana
And since armor doesn't protect against skills it's all yours. Mana costs are pretty high, though, but Torchbearer can afford it easily.
Variant 2: Frozen Purgatory
You met generals that care for their troops and push them to ridiculous levels of toughness ? Tough enough to even lay their dirty hands (and broadswords) on your person ? Well, you're responsible for hell freezing over, so you can't have that. Get the Fire Nova skill for even more area damage and maximize Frost Nova to ensure everyone stays inside your Circle of Fire. Slow down everyone who wants to leave the party early and Deep Freeze anyone trying to teleport out.
Frost Nova 3
A maximized Frost Nova extends the freeze stun to 10 seconds for creeps and towers, which is a near death sentence for anyone affected and standing in the wrong neighbourhood. Demigods stay frozen for 3 seconds, which isn't popular amonst the victims either. Three seconds gives you plenty of time to klonk some heads or to teleport away, in case the opposition looks too overwhelming.
Torch Bearer emits an aura slowing down nearby enemies' attack and movement speed by roughly 5% each level. Also, you and your allies regenerate mana faster (by a not yet known amount ). This is both a getaway skill and an invisible suit of armor, permanently reducing melee damage.
Deep Freeze 1
In this branch we simply don't have enough skill points to make most use of Deep Freeze. But one point offers you plenty of advantages and it's criminal to neglect them. This skill is an interrupt. You can't use it to kill anymore, but you can use it to keep victims from staying alive by denying them their teleport, health potion, whatever. And 350 mana for an interrupt is dirt cheap.
Fire Nova 3
Expensive, but instant 800 damage in a large area around you and whirling smaller units around means that enemy generals might basically leave their army at home for all the difference they make. Keeping lanes free of rubble - or transforming Rooks tower farms to rubble - has become much easier.
Well, we got one point left. That can be spent in Biting Chill, Enchanced Attributes, Fire Aura ... whatever catches your fancy. I suspect that Biting Chill is the best place to put it ... after all, it's a level 15 skill.
TB is squishy and a mana hog. Your choice of items should reflect that. You also deal most of your damage using your spells, not your ranged auto attack. So armor, Mana regeneration, health potions and bitch-out items are your best bet. Heart of life is everyone's favorite, I guess.