WordNet sense 1 (designed or tending to discredit, especially without positive or helpful suggestions):

damaging, negative

WordNet sense 2 (physically or spiritually devastating; often used in combination):

devastating

WordNet sense 3 (of a substance, especially a strong acid; capable of destroying or eating away by chemical action):

caustic

WordNet sense 4 (causing injury or blight; especially affecting with sudden violence or plague or ruin):

ruinous

WordNet sense 5 (wreaking or capable of wreaking complete destruction):

annihilative