I'm not 100% sure it can be done with iOS but I know android is capable of using swipe. Imagine if you arranged your skill tree so your best 4 attacks were in the left column, best 4 defense skills were in the middle, and right were heal. A swipe through all 4 rather than 4 taps would save time in battle.

Also possible would be to draw a combo you'd like to use. Say drawing the letter M for melee would fire off damaging skills simultaneously or in rapid succession.

Thoughts?