Malevolent Naix (lane)

This guide is really good, it has won me several games. I would like to clarify something though. 1 int gives 13 mana, so you actually get 325 mana. Other than that good guide. Peppo's S&Y comment is worth mentioning, as the attackspeed from the yasha is amazing, let alone the 16% movespeed.

The skill build is kind of random in my opinion. I usually go for the 2-1-2-1 build by level 6 and leave Feast at 1 (or 2, depending on my item progression and if I have to jungle) until level 12. Then, depending on the situation, I either max out Rage (more common; teamfight oriented) or Open Wounds (ganking oriented) by level 8.

The item build is nice but I would put the Orchid Malevolence between the situational items: I see a lot of competitive players going for a Sange and Yasha after the Armlet since the attack and movement speed make Lifestealer a very strong chaser and solve one of his major issues, which is kiting (you don't need more damage from other items anyway, so even if SnY gives little damage you are okay); other options could be the Desolator or a quicker Skull Basher since you should already have high movement speed. I do like the Orchid and sometimes (versus Storm Spirit, Queen of Pain, Puck etc.) buy it as a core extension, but not in all situations.
Also, all competitive players like getting a Drum of Endurance after the Phase Boots if they don't buy a Hand of Midas: it's a very cost-efficient item that gives a lot of stats, more movement speed and an active ability that can turn the tides of a fight/chase. You don't really need such an early Armlet of Mordiggian anyway.

Still, since it's a laning Lifestealer guide, I'll give you a +1. Teach those new players to lane this Hero, as his skills make him very powerful at killing in the laning phase. :D