adjective
drastic
DRAS-tik/ˈdræstɪk/
Severe or extreme in action or effect.
The drastic pruning leaves only short stubs of the leafy shrub.

Etymology
The Greek adjective meant effective or forceful. English first applied it to medicines with powerful effects on the bowels, then broadened it to severe measures or changes with strong effects.
In context
he's made some drastic changes to the hill troops lives. the biggest one leading them out of the forest into Matt Noah's idilic home.