Toxic nests are placed as a calldown ability from Abathur's top menu. Abathur can store up to 5 of them at once, creating a new one every 20 seconds if there are slots available. They can be placed anywhere the player has vision to.
They explode (hotkey X) to deal 125 damage to enemies when they pass. The explosion can be set to autocast, or manually triggered. Toxic nests also provide creep.
Enemies damaged by Toxic Nests drop 50% additional Biomass and slow enemy attack and movement speeds by 75% (20% for heroic units) for 5 seconds. Toxic Nests have a 50% chance to respawn on death. Toxic Nests can not be targeted by the enemy.
Enemy Drops Double Biomass Chance Mastery: enemies, killed on Toxic Nest, can drop double biomass with a chance 1% per each mastery point.
Mastery: +1% chance per Enemy Drops Double Biomass Chance mastery point. Up to a maximum +30% chance