Gnartian Player Class, Mastermind

MUTANT MASTERMINDS (MM)

Start with one Random Good Mutation, plus one per CON bonus (three Mutations for 18 CON, two for 16, 17, one for 13-15).  One Mutation is gained for each lvl of experience.  To determine, the Player rolls for as many Mutations as the PC has lvls, then chooses one not already possessed from this list.  Each Mutation may be used no more than 1/day, and the total number of Mutation uses/day is equal to XP lvl + CON bonus.  Upon reaching 12th lvl, Masterminds automatically gain any one Mutation of their choosing per lvl.  Immune to Radiation Sickness, Radiation damage is halved (Save for 1/4), Immune to Mutation Defects/Drawbacks, able to communicate with sentients via Telepathy, though this is widely considered impolite.  Masterminds have an enlarged frontal cortex, usually making them recognizable as such, and has led to such appellations as Craniacs, Braniacs, and (less complimentary) Butt-Heads.  MM Attack and Save as Thieves, can use any weapon, but cannot wear metal helms or armor. 

Houserules: 

Saves vs Radiation = Paralysis/Poison, Save of 20 = gain Good Mutation, Fail of 1 = Bad Mutation

Saves vs Mutation Attacks/Effects = Spells/Magic.  CON bonus applies, or WIS bonus vs Mental Effects, domination, etc
Radiation 'Class" I -X, causing this # of d6 damage, Save for 1/2

If exposed to Radiation Class greater than the MM's level, his CON bonus is applied to his chances to gain a Good Mutation (instead of a natural 20, a MM w/an 18 CON would gain +3; so a Save vs Radiation of 17+ would grant a Good Mutation, if it doesn't kill him!)

My interpretation is a Mutation of the original stock:

http://www.savageafterworld.com/2009/10/new-character-race-mastermind.html