Abount the OD counter: using a green art will double the counter for each hit of the next art. So, green art -> Hellfire (12 hits) = 24 to OD counter. About TP: You'll always need 3000 TP to extend OD. Using a purple art will add 10x OD counter to TP. So, using Trash Talk at max morale and max counter will give you 3x200 + 10x100=1600 TP. Keep an eye on arts/skills which add TP.