How do they work? Does E'ci's blessing give E'ci's Familiar rk 5 effect passive? What does Kerafyrm Familiar does? Just damage on instent spells? Does Kerafyrm favor do anything besides draining AA points? Is Improved Familiar any use when you have Kerafyrm?
Blessings just open the way to Kerafyrm familiar. Kerafyrm is the familiar you should always use, except when you have a bard in a group, then you may change to improved. The effect description from Kerafyrm is a bit confusing: works on every instant spell, but not insta cast, just all nukes (no DoT allowed, but we don't care). So Kerafyrm affects all our damage spells, a little bit more than improved, but Kerafyrm don't stack with bard song. I hope it helped.
Has been a long time I don't play my wizzy, and I'm not used to group with bards, but I think it's Aria. The song that improves cast dmg. If you're using bard to improve your caster's dps, use improved. For the rest, Kerafyrm. Beimeth, Axxius and the rest of elite wizards in this forum will give you a more elaborate answer than I'm capable of.
Aria of Va'Ker (and only Aria; the Aura of Va'Ker, or Echo of Va'Ker won't do - they have a much inferior caster focus). If you have it 100% of the time, then you don't need the DD focus from the Kera familiar and can use the Improved one for the +crit focus. However, you need to be really sure that the bard stays with you and plays it. For example, if the bard is pulling for the group and runs away to fetch the next mob while you are killing the current one - then you lose your biggest focus, and that's not good and you'd be much better off with Kerafyrm.
Alright, I sort of feel like "wasted" a good numbers of AA points but its good to know its at least usefull if (and he almost always is) the bard is pulling.
