'Devise' in the Bible

In a time of tranquility he will enter the richest parts of the realm, and he will accomplish what his fathers never did, nor his ancestors; he will distribute plunder, booty and possessions among them, and he will devise his schemes against strongholds, but only for a time.

He'll encourage himself against the southern king by raising a large army. As a result, the southern king will mobilize for war with a large and powerful army, but he won't succeed because they will devise elaborate schemes against him.