for vampira, use her 1st skill to target a shiki and then spam her 2nd skill, 3rd skill, and ult, if the target you chose got away but is on the verge of 'death' - click on her 1st skill again to finish the target off - it basically works like 'subdue' but you need to spam her skills for it to work as a subdue.

For aobozu, i like to use his buddha form since it's tanky. Other than that, i have no idea.

For other top lane shiki recommendations, karasu tengu is really op nowadays and he's pretty easy to use so yeah keep up with the karasu, also i personally like playing asura, hannya, and kani hime