Reap what you sow-- paradoxically, instantly after you sow it.
This build turns Sevagoth into a nuking frame-- you cast Sow, then immediately afterwards you cast Reap to capitalize on the damage potential.
[Transient Fortitude] is Rank 8 because at Rank 10 you literally won't have enough time to finish the casting animation of Reap before Sow expires.
Haven't tried this in Steel Path, but in normal this build completely evaporates huge groups of enemies.
Given that this build does not use Duration, [Sevagoth]'s 3 ability Gloom, is not usable. Go nuts with Helminth.
This build can struggle to keep energy up, so Zenurik is recommended but not required.