en_tn_condensed/isa/28/21.md

Yahweh will rise up

Yahweh preparing to act is spoken of as if he were sitting and then rising up. (See: rc://en/ta/man/translate/figs-idiom)

Mount Perazim ... Valley of Gibeon

These refer to places where God miraculously defeated enemy armies. (See: rc://en/ta/man/translate/figs-explicit and rc://en/ta/man/translate/translate-names)

he will rouse himself

"he will become very angry"

his strange work ... his strange deed

These two phrases mean the same thing. This work is strange because God is using a foreign army to defeat the people of Jerusalem rather than helping the people of Jerusalem defeat their enemies. (See: rc://en/ta/man/translate/figs-doublet)