The Tavern

First time in a long time that I got anywhere with Dithmenos - just grabbed my first rune ever under his guidance. Is there any other reason besides extending the length of shadow form to train invocations? I don't intend to use it a lot, if at all.

I seem to recall that it effects the chances of, and damage done by your shadows, I could very well be wrong though, that may have been just something that someone suggested.

I would have thought so, too, but Wiki says that the damage depends on the relevant other skills - weapons or spells. So it probably is just the shadow form duration - I better stop training the skill now...

Invocations with dithmenos reduces the failure rate on shadow step and shadow form and increases the duration of shadow form, that's it. Shadow mimic chance depends only on piety and damage depends on the weapon/spell being mimicked and your experience level. Not a huge priority to get more invo once shadow form is reliable, though if you plan on doing some sort of extended ninja thing (say, orbruntomb), it can be useful to have extra so that it lasts longer and you can shadow form repeatedly without having to deal with increased failure rate from draining.