Which weapon are you using? If you don't do that much damage, take a look into elemental damage; if you really want to make sure everything dies, just have one weapon with corrosive elemental damage, one weapon with just burn damage, and one with shock damage. That would pretty much cover everything. As for damage mods, if you can get "Primed 'x'" of any mod that increases crit damage, crit %, or damage, spend the ducats to get it. Also, get multishot mods. Those things not only amplify damage by a huge amount, but they also increase status % chance. Saturn is mainly Grineer based, iirc. If you have a weapon that has corrosive elemental damage (Toxin + Electric), Grineer drop like flies. Here's a picture of my build; it's not for Soma Prime, but it decimates all Grineer pretty quick, even Nox. Since pretty much every Grineer has a huge hitbox for their head, this weapon setup just steamrolls all of them. Edit: My build is nowhere near end-game build; I don't have Primed Fast Hands, and I'm probably going to replace Fast Hands with Primed Shred when I get it, but this build got me through everything so far. Zhuge is one of my favorite weapons, but as of right now, I'm more focused on getting my Vectis Prime built up to near end-game status. I'm thinking I need probably 2 or 3 more Forma for Vectis Prime, because I'm building it for max crit percentage, and max crit damage. As of right now, my crit damage is pretty high up there (I think it's at 5.55x), so it's enough to 1-shot mid-level to mid-end level enemies. I'm trying to get an Argon Scope just to ensure that I can 1-shot everything in the game minus some of the end-game bosses.

Enemies have resistances to different damages. But in later game you'll find elemental damage is better as it is more powerful against certain enemies than others and they have special procs that boost its capability. The codex gives you information on all this. The Wikia also provides an indepth explanation on what element is best for who. A few youtubers also cover this topic. For a hint, Fire damage does more against infested than against others, but for grineer i would use puncture based weapons and radiation and corrosive damage.

I've noticed you can combine elements to make a blend. Is this weaker compared to have straight fire for infested? Probably explains why infested seem not to bother me as much. I have volcanic edge on my melee weapons and use them frequently. My oberon's abilities seems to be better against grineer for this reason as well. Thanks for the info

No its just a unique damage type. Its stronger against certain enemies but then weaker against certain other types.