Ishida's Strategy, the 20-Second Offense and Defense

Uryuu and Renji continue fighting against Szayel and with Renji's help, Uryuu pulls out a secret weapon to use against Szayel. The attack seems to be a success at first but Szayel has his own secret technique.
Meanwhile, Grimmjow appears before Nel with Orihime in tow. What does Grimmjow have planned? Will Ulquiorra have something to say about it?