This is not for the nice little children, you either have to be very naught or incredibly un/lucky.
Curse mark chakra - The user gains a pool of cursed mark chakra that can be released into the user's body at will. (CP Gained: 30 for 1 feat, 65 for 2 feats, 100 for 3 feats. Restricted to 1 feat/rank from chunin to S-rank).
1st State - Activating stage one of the curse mark increases the physical abilities of the ninja. When activated dark marks, which vary mark to mark, spread around the body. (10 CP stat boost, configured as the user wishes) 10 CP/round
2nd State - Further increases physical abilities. The 'cracks' spread till they cover every inch of skin, the after-effects of this vary. (20 CP stat boost, configured as the user wishes) 20 CP/round
3rd state - A further evolution of the curse mark, initially achieved through intense emotion or near death. When activated, the user's appearance becomes even more extreme. (40 CP stat boost, configured as the user wishes) 40 CP/round
Note: curse mark levels can include a fluffical transformation that is manifested largely through the stat boosts. Boosts must be taken in order (CM 1, CM 2 both feats, then CM 3 feats). All normal rules for boosts must be met.
Mutation - Each curse mark grants a unique ability which varies in versatility, power, and CP cost. (Make it up but will require approval.) Read this page for information on unique feats.