mount something against someone or something
to create or instigate something against someone or something. The prosecutor mounted a questionable case against Robert. The state mounted a very complex case against the company.
mount something on something
to place or attach something onto something. Mount the butterflies on plain white paper. Sue mounted her favorite stamps on a display board.
mount up
1. to get up on a horse. Mount up and let's get out of here! Please mount up so we can leave.
2. [for something] to increase in amount or extent. Expenses really mount up when you travel. Medical expenses mount up very fast when you're in the hospital.