ruinous

adjective

1
causing injury or blight; especially affecting with sudden violence or plague or ruin
the blasting effects of the intense cold on the budding fruit
the blasting force of the wind blowing sharp needles of sleet in our faces
2
extremely harmful; bringing physical or financial ruin
a catastrophic depression
catastrophic illness

Also useful for “ruinous”:Unscrambler— Rearrange the letters in “ruinous”