Smoke bomb is great.
Body of fire is very powerful, but probably a bit too expensive for an alchemist (that does not really need to invest massively in willpower).
Maybe I am missing something, but I have real problems with the 2 other talents.
Heat is completely useless IMO. Compared to channel staff, it is less powerful as soon as you have a decent yew or elven wood staff and some phys_power items. And it only has drawbacks compared to it.
Larger mana cost (10 vs 5)
Larger CD (5 vs 0!)
DOT while channel staff deals all the damage immediately
Fire, while you can change the damage of channel staff by 'x'changing your staves
Can harm the golem while CS is friendly and can jump over him.
And, which is more important, less powerful in the mid/late game.
I would really suggest to boost this talent. It can be either by improving the damage, by adding side effects (stun, for instance), or, maybe the best, by making the spell beam, etc...
Fire storm also is completely useless, but for other reasons. It a very good and powerful spell and I would love to have it as an archmage. But it is not golem friendly and, as there is no way to tell this stupid golem to keep away from the fire, he will continue to be by you and you can rapidly help to destroy him by using this spell
. One solution would be to make the spell golem-friendly. But I would rather suggest to replace it by a new spell, using original mechanisms.
Spark rain (or conflagration).
Send fire sparks over a radius 3 area. Each spark has a probability (50..90)% to set ablaze his target. While ablaze, a character will get x damage per turn for (5..9) turns. Each burning character has a probability (15..25)% per turn to expell a spark that will set ablaze another target in a radius (1..3) area. Friendly characters cannot be set ablaze.
Damage x is not intended to be large, and it has no real necessity to scale with talent level (but it should with spellpower, of course). The spell works by propagating the conflagration among npcs.
Probably requires a 60 or 80 mana cost, and a 30 turns CD.
For characters that are indirectly set ablaze, the duration should not be equal to the original duration, which would make the spell too powerful (or the conflagation probability should be reduced). I would suggest that the duration is equal to the number of remaining turns on the source of the spark +1. If the target is already ablaze, his burning duration is increased by 2 (or 1) without damage stacking.
Even with a small amount of damage per turn, this could be a powerful AOE spell in front of a large number of foes. And, for sure, a good replacement of fire storm.