if u got tier 5 urahara, then u only need 1 intermediate fury stone 4 primary and 1 basic to get him to 100% [or 6 primary fury stones] not sure for assaulter to get 100 fury after urahara special. since if he crits u get more fury and if u fail to crit u get less fury. but it wouldnt be more then 6 basic fury and thanks to this valentine's event basically everyone in every server got a 6 basic fury stones. which will make csb and such even harder