Thamuz: Best build, Counters

Grand Lord Lava

Thamuz's Basic Attacks have a chance of 10%–60% (scaling with Lava's Rage) to conjure Lava Energy beneath the target that erupts after a brief delay, dealing 55 (+60% Total Physical Attack)(+8*Hero Level) True Damage. Basic Attacks that don't trigger Lava Energy increase Thamuz's Lava's Rage.
While Thamuz is without his Scythes, he gains 25% Movement Speed. After retrieving his Scythes, his next Basic Attack slows the target by 30% and is guaranteed to trigger Lava Energy.

Molten Scythes

Thamuz tosses Scythes in the target direction. After traveling a set distance or hitting the first enemy hero, they deal 120 (+60% Total Physical Attack) Physical Damage. The Scythes will then slow nearby enemies by 30% and deal 45 (+20% Extra Physical Attack) Physical Damage every 0.5s.
After leaving Thamuz for a short time or reaching a set distance, the Scythes return to him, dragging enemies along their path toward Thamuz. Thamuz can move toward the Scythes or cast the skill again to retrieve them.

Chasm Trample

CD: 8

Thamuz jumps to a designated area to deal 230 (+60% Extra Physical Attack) Physical Damage and slow the enemy units by 25% for 2s upon landing.
If the Scythes are still travelling, they will return to Thamuz and Molten Scythes will reset its CD instantly.

Cauterant Inferno

CD: 38

Thamuz spouts the lava within, dealing 300 (+80% Total Physical Attack) Physical Damage to nearby enemies and creating a Cauterant Zone around himself. The Cauterant Zone lasts 9s and deals 30 (+10% Extra Physical Attack) Physical Damage every 0.5s to enemies in the area.
Meanwhile, Thamuz gains 800 (+50% Extra Max HP) HP, immediately healing for the same amount, and gains 60% Attack Speed. Each time his Basic Attacks or Scythes deal damage, he recovers 1.5% Max HP.