Some Advanced Questions

1. I would say AA but I'm not 100% since I never use it.

2. The ones I usually use are: Nimoth chest armor, blood of the fallen, Narmoth ring, unbreakable boots, banded armor, narmoth's ring, and grofling's warplate.

3. Plenor give a % of mana per second, which makes it inferior until you get your mps up. I never need more than vlemish and plenor, and blade of the serpent is probably all you'll need if you are willing to give up a favor slot.

but Vlemish only gives 15 mana / second, that's not that much

+ Plenor gives 700 mana more than Vlemish

believe me, 15 mana per sec is a lot, but there is also the aura, which is always nice.

at that point, % regen is miniscule, about + 5ish per sec, and that is worthless, but the 15 is a lot

What are the other good mana items available, for example if Im planin an infinite mist build for LE, I need more than Velmish and Pleanor. So what other mana items I can buy, of course that are realistic in a balanced game ?

Well, you could use Scaled Helm, it adds +4 mana per tick and is super cheap.  After Vlemish and Plenor, ignoring favor items, youre looking at more expensive stuff like the artifacts or Hungerlings Crown. 

It gives 525 more mana, but produces about 12 more mana per second. 525/12 = 43.75 seconds before you make back the raw mana boost. Not that long of a time. In almost every situation, Vlemish is better.

there is also magus rod. but i dont do mist build with erebus so i dunno if something else is used. i do assassin ereb and my mana items are vlem, plen and magus. magus for 5 secs reduces skill cost by 50% and gives 50% mana regen, so its very nice to have since ereb's skills cost so much mana.

So what about #1 & #2?

it has been all answered in the first post.

btw. why should anybody do a mist build? trying to convince others ereb is underpowered? (not that i suggest he is overpowered).

Yeodan:

1.  I play generals 99.9% of the time so i don't know.

2.  well the obvious ones: Banded, nimoth, hauberk, groffling (i like to use these 4 for my oak builds)

then there's unbreakable, godplate.  Bloodstone & Narmoths (the rings are only good if you have high autoattack speeds)

There there's:  Girdle of the giants, bulwark & all fathers ring.

3.  Vlemish is better up front (usually) becuase it provides regen whereas the plenor doesn't provide much regen at all unless you already have vlemish. 

One thing to point out though is that on Leviathon, the dynamics change since there is a +mana regen flag on the map.  This means that Plenor is the best one to get first.  For some demi's just getting plenor is enough for this map.

first question has been answered for abouth 1/5th and he wasn't even sure of it

you are right, the first question was not fully answered and i must admitt i only observed it being triggered by AA, no matter what demigod. as there are favor items with effects that can be triggered also off specials i don't know for sure if this may be here the case too.