Normally I don't suggest changes, but this one seems easy and logical, so here's my spin. Hope no one already mentioned this before.

All the change enduring brew needs, is change the healing it gives, to heal energy. Keep everything else the same.

Instead of enduring brew healing for 3xx then take a DOT for ~2xx over 6 seconds, or whatever the amount, enduring brew recovers 40-60 energy (exact amount to be determined), and hurts the rogue for xxx and maybe reduce healing by xxx as well.

This helps alleviate some of the problem of energy starvation in assassins, it makes a useless skill relatively useful, and its far up in the tree so that it is mainly exclusive to assassins.