Burston Prime Incarnon

With it's Incarnon Genesis, new life has been breathed into a (very) old favorite, turning it into a very competent weapon capable of clearing rooms in seconds even in high-level Steel Path Missions. The alternate fire mode is a fully automatic rifle with a small AoE; excellent for clearing tightly packed crowds of enemies.
Evolutions

Take Fortress Salvo, Kinetic Battle, and Absolute Valor.

In Evolution 2, Forceful Finality is meaningless, as you will never be emptying the entire magazine. The enormous increase to base damage is shared between both options, and the huge punch through bonus is very nice if your warframe meets the 450 armor requirement.
In Evolution 3, both alternatives to Kinetic Battle have the same demerit as Forceful Finality. Increased magazine size and reload speed are meaningless when we never need to reload.
In Evolution 4, Reaver's Rapture is a non-option, as the bonus is lost when activating Incarnon form. Hopefully this is a bug, as increasing only non-Incarnon form damage is effectively meaningless.
In Evolution 4, Fatal Affliction is a valid alternative. However, it shouldn't be taken in most situations for a few reasons:
    The Incarnon form has a very impressive base 3x critical multiplier. Taking Fatal Affliction would drop the final critical chance from 150% to a mere 84%, squandering a final 6.6x multiplier and tier 2 crits.
    Critical chance dropping below 100% also prevents us from taking full advantage of [Hunter Munitions], which comprises the bulk of our damage, especially against armored targets.
    Finally, the Incarnon form drops all IPS in favor of pure heat damage, meaning the only statuses we can proc while in Incarnon are Heat, Viral, and Slash, leading to a maximum 120% damage without a primer; far less than even a tier 1 crit's 6.6x multiplier.

NOTE: Non-primed or galvanized mods will be perfectly acceptable alternatives, but prioritize getting Galvanized Chamber quickly, as it's roughly a 2.5x damage increase over Split Chamber.