Rath is a ranged attack ground unit with mercenaries. His skills focus on cursing enemy heroes by reducing their effectiveness in battle.
Rath is a very good counter hero to many of Enchantress’ skills. His divine deals extra DMG to heroes who have had their skills dispelled through her aid or divine skill..
The most effective equipment to apply to Rath would most likely be the Arcane Tome to capitalise on his wizard mercs, or the Thorned Bow, which will provide another SPD debuff against enemies in conjunction with the SPD debuff his active skill causes.