It's basically the same as the level 50 rotation except Ley Lines is now a button to push.

The most useful thing I've found to do with Sharpcast is to let me multi-dot on packs of exactly 3 mobs.

Sharpcast T1 -> Switch target -> T3 -> Switch target -> Normal rotation except now I'm using Thundercloud to keep T3s rolling on all three targets.

Sometimes Thundercloud doesn't cooperate with you, but usually it does.