Mutations are a passive bonus that gives huge positives and small negatives. With Class Freak ⭐⭐⭐ the negatives drop by 75%, and with Starched Genes ⭐⭐ mutations stop disappearing when you use Radaway. This guide shows the 7 mutations every build should have.
How to lock in mutations
Step 1: take Starched Genes 2★ in Endurance perks. This "freezes" your mutations — Radaway and RadShield can no longer remove them. Step 2: take Class Freak 3★ in Luck — mutation penalties are reduced by 75%. Step 3: stay in a nuke zone or eat Strange Meat — mutations appear at 5% chance per radiation tick.
1. Marsupial
Pro: +20 carry weight, +2 jump height. Con: −4 Intelligence (with Class Freak — basically 0). Mandatory for every build — the single most useful mutation in the game.
2. Speed Demon
+20% movement and reload speed. Con: thirst and hunger drain 1.5x faster. Perfect for Commando and Heavy.
3. Electrically Charged
Chance to electrify enemies who hit you in melee. With Strange in Numbers in a group, x1.25 chance. PvE must-have.
4. Adrenal Reaction
+25% weapon damage at low HP. Perfect for Bloodied builds — stacks with Unyielding and Adrenaline.
5. Bird Bones
+4 Agility, slower falling. Con: −4 Strength. Must-have for snipers and bow hunters.
6. Carnivore
Meat gives x2 buffs and doesn't need cooking. Con: vegetables stop working. Convenient for Bloodied builds that eat only meat.
7. Herbivore
Same but for vegetables. If you prefer Cranberry Relish or Tato Salad — take this.
Where to buy serums
Serums guarantee a mutation without any negative effects. They are expensive (~3000 caps at Whitespring), but they save a lot of time. On Gameflip they go for $0.50 each.
Bottom line
Minimum kit for any build: Marsupial + Speed Demon + Adrenal Reaction (Bloodied) or Electrically Charged (Full HP) + Bird Bones (Sniper) or Herbivore (Caster).