Death Resistance (+1): Built-in skill. SP is very scarce. If you keep leveling up without PK, you can max it out. Or if you don't level up and do PK, you can reset your stats. Blood Rage (+10): Signature skill of Red Eye. Don't even bother playing if you're not going to max this out (*^__^*)...
Anger Eruption (+10): Optional, usually +10 is enough. There's no need to max it out due to SP limitations.