The 4 Beast 6 Warrior build makes use of summons from Werewolf, Razorclaw and Poisonous Worm plus the Beast synergy that boosts the damage of summoned units.
The additional units overwhelms your opponents, punishes open forters and those economizing with a lose streak.
The Lineup
Synergy
The Beast Warrior build boasts an impressive 6 synergies. Additional damage from Beast, durability from Warrior, attack speed from Glacier (mainly for your Berserker), Lifesteal from Warlock, a bit of silence from Human and extra damage for your Doom Arbitor from Demon.
With four 4 Cost pieces this build can be quite expensive make. If you don’t end up rolling a Doom Arbiter, you may use a lower cost Warrior piece as a substitute.
Like with other warrior builds, this composition is particularly strong against physical damage based builds. Should you face magic damage, you may consider adding a Marine piece for some magic resist. This can be for your 10th piece, or in desperate times you can sub out Doom and drop down to (3) Warrior to help you survive a heavy magic damage lineup.
Positioning
You can use a simple straight line positioning for this. Just make sure your Berserker, Desperate Doctor, Poisonous Worm and Razorclaw is in your backline.
If you have a Doom, consider placing him in front of your Berserker to quickly focus down an enemy piece.
Take note of the positioning of your Pirate Captain and Werewolf, as they can be placed to help silence key opponent pieces. If you find that these pieces are dying before getting their skills off, consider placing them further away from the center of the board.
Items
Defensive
Doom is a great carry of defensive items. Werewolf is also another good candidate.
Offensive
Stack them on your Berserker. Aim for a Frantic Mask, it is particularly good on Berserker due to how his passive skill works (applies attack speed stacks on auto attack against same piece). As for magic damage, Doom/Swordsman are great picks.
Mana Regen
Pirate Captain is your primary AoE crowd control. A Refresher is great on him. A bit of mana regen on Poisonous Worm will help it get more summons on the ward. Lastly, your Desperate Doctor can also benefit from charging up faster to get its stun off earlier.
When to Build
Whilst the Beast Warrior build is a strong all round strategy. A drawback of this build is that its pieces can be quite contested. Pirate Captain, Werewolf and Tusk Champion are often great frontline picks.
Berserker is a key piece in any Glacier build. Razorclaw is a popular pick for Druid frontlines such as Hunter Feathered and Druid Assassins. Not to mention you will be competing against any player that is also going down the Warrior build path.