Alma 43:8

for hehold, his designs were to stir up the Lamanites to anger against the Nephites; this he done that he might usurp great power over them; and also that he might gain power over the Nephites, by bringing them into bondage, &c.

His plan was to make the Lamanites angry at the Nephites. He did this so he could have great power over them. He also wanted to gain power over the Nephites by making them slaves.

His plan was to stir up the Lamanites to rage against the Nephites. This way he could seize power over them and eventually conquer the Nephites and make them slaves.