This is a damage sheet I found from update 11. I dont see anything newer so im sure its the same for update 12. Im gonna break down how the killing system works. Very helpful for all the new players, and your WELCOME!
1. Grineer Armor - Best: Puncture (+50%) Corrosive (+75%) Good: Toxin (+25%) Do not Use: Slash (-25%) Blast (-25%)
2. Corpus Shields - Best: Megnetic (+75%) Good: Impact (+50%) Cold (+50%) Do not Use: Puncture (-25%) Radiation (-25%)
3. Grineer/Corpus Flesh (Health) - Best: Toxin (+50%) Viral (+50%) Good: Slash (+25%) Do not Use: Impact (-25%) Gas (-25%)
4. Robotics Health - Best: Electric (+50%) Good: Puncture (+25%) Radiation (+25%) Do not Use: Slash (-25%) Toxin (-25%)
5 Infested - Best: Gas (+75%) Good: Slash (+25%) Heat (+25%) Do not Use: Radiation (-50%) Viral (-50%)
You have three tabs apply mods accordingly and supercharge them and use formas for the right polarities for proper installments as well to get more upgrade points.
Also its important to rank your damage mods. Try to get serration to rank 7 atleast. Punch through is also important. It bypasses armor and goes right to the flesh. You can also shoot through doors when its high enough.
Primary Types/Combined Types
Heat + Cold = (Blast) Heat + Electric = (Radiation) Heat + Toxin = (Gas)
Cold + Heat = (Blast) Cold + Toxin = (Viral) Cold + Electric = (Magnetic)
Electric + Heat = (Radiation) Electric + Cold = (Magnetic) Electric + Toxin = (Corrosive)
Toxin + Heat = (Gas) Toxin + Cold = (Viral) Toxin + Electric = (Corrosive)
Blast (Fire+Cold) Stun/Knockdown
Gas (Fire+Toxin) Poison AoE
Radiation (Fire+Electric) Confusion (difflculty targeting)
Magnetic (Cold+Electric) Reduces Shields
Viral (Cold+Toxin) Reduce Health
Corrosive (Electric+Toxin) Reduces Armor
Ill keep this updated once i see new updates. As of right now this is current. Post your builds, what build works best for you against which fraction?