Multiplicative Bonusses

If I run a CI build with Avatar of Fire, and have the following gem setup at Clvl 60:

Reave (16) + Melee Physical (15) + Melee Damage on Full Life (15) + Weapon Elemental Damage (16) + Concentrated effect (15)

Let's for simplicity's sake i have a weapon that does 100DPS.

Would the damage be as follows?

100*(1+0.6)*1.44*1.45*1.55*1.64 = 850dps, all of it fire damage?

Not without an additional source of damage conversion.

Avatar of Fire only converts 50% of your physical damage to fire damage, so you'd need something that converts another 50% of physical damage to fire damage to get 850 dps. With the setup as you describe it, you'd only get 425dps.

(also, the MDoFL multiplier should be 1.44 at level 15, not 1.45)

It would be half of that because AoF only converts half your phys.

Molten Strike then?

That works but you should swap concentrated effect for fire penetration. It's worth a lot more against fire resistant mobs.