Good builds for Beastmaster

I think Beastmaster has 3 roles that he can fill extremely well, and the build differs for each of them. Obviously he is in the offlane for all of these roles (maybe he can roam the his boar, not sure on that).

Role #1. Wolves Need No Armor
This is the somewhat stereotypical build described by hamster. You become an unstoppable splitpushing powerhouse with some global utility for your team. You are the designated split pusher when enemies are trying to take objectives. Due to the nature of your boar, the other team requires their positions 3+4/5, or a lone position 1/2, to defend from you (if your item timing is good). Definitely a good build, but not the only option. This build does not work if you lose your lane or if their team can easily deal with your summons/outpush you.

Role #2. Position 3 Doom
We all know that low position deathball Doom that is so difficult to play against. Beastmaster can do the same thing, and he can do it better than Doom can. Things like Drum of Endurance, Force Staff, Guardian Greaves, and Vladmir's Offering are found in this build. Aura stacking and utility between the hawk/your 2k gold items make your team really hard to fight against. Beastmaster is unusually good at this compared to other heroes, mainly because of the hawk. Necronomicon is only really bought for this build of you need the detection, but you're probably better off with an aghs NS if that's your goal.

Role #3. Initiator
Hey, let's have the guy with the incredible but short-ranged BKB-piercing disable quadruple his effective cast range! This is in fact a good idea. This build buys Blink Dagger and focuses on finding strong ult opportunities and taking advantage of them. Blink Dagger, Aghanim's Scepter, Blade Mail, Shiva's Guard... you know... initiation stuff, along with things to help you survive your initiation. This build does not buy necronomicon.

Obviously this isn't a "pick one" situation. Maybe you need a Heaven's Halberd for that PA, or a Black King Bar for that silencer who can out-react to your higher cast point ultimate. But these aware the basic, general builds to go off of. Necronomicon is fantastic on him, but not absolute. It can very well be a game-losing item if an enemy TA or someone similar is able to farm them easily.