Starts with 6 charges.

Bloodpact
Bloodstone gains 1 charge each time an enemy hero dies in 1600 AoE
Each charge gives 1 Mana regeneration per second
When the bearer dies, Bloodpact restores 400 + 30 per charge HP to allied units in 1675 range, and Bloodstone loses a third (0.333) of its charges (rounded down)
While dead, the bearer gains 1800/1800 AoE vision at the location of death, and gains experience in 1000 AoE at that location
Gold lost on death is reduced by 25 per charge
Respawn time is reduced by 4 seconds per charge
Bloodpact only functions for the highest priority Bloodstone in the inventory