Just to chime in with Never Ending Pew Pew and ElectronDF, use Jamba's auto-follow to resume following once done. But its a good thing that channeling breaks the follow, that way your spell keeps on going...

Not to mention it just looks really really kewl to have 5 Drain Life/Soul casts going on at once with the proper formations, or a mix n match there of.. But what am I supposed to do with all these shards!!?? hehe