One on Many Chart

ONE ON MANY CHART
Actions                        Modified Difficulty                       Toughness Increase
1                                    DN+2                                              -
2                                    DN+4                                             +2
3-4                                 DN+6                                             +3
5-6                                 DN+8                                             +4
7-10                               DN+10                                           +5
11-15                             DN+12                                           +6