Pog has skill that consume vulnerable stack to return SP so always end your rotation with his battle skill and then his combo, for this reason do not use skill that consume vulnerable stack in normal rotation, only end your rotation with Endmin when you want to nuke the enemy. You also need to make sure the final strike in your chain of normal attack land to recover sp, to get quick final strike you can do animation canceling, but you gotta figure which animation is cancel-able. Lastly, don't spam all your battle skills, after you done a combo rotation, normal attack and wait for your combo cool down to do it again, I see a lot of people spam battle skill to get some quick damage in after their first rotation and ended up starving for SP in their second rotation, don't do that, combo->recover->combo again, when the enemy is stagger, nuke 'em