He's used as an anti-carry, and he does this incredibly well because he can take the enemy carry out of the fight for over 5 seconds and then plague them with massive miss chance (while doing insane damage himself). General item build to shoot for is phase, soul ring, magic wand, blink dagger, and drums of endurance, with scepter as luxury. Remember his earth panda carries all auras. If you're still farming after that and the game is still going on, shoot towards either a Necrobook if you have the micro skillz or Shiva's Guard otherwise.
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