Whispike Survivors - Sword of the Necromancer

To make this really easy you can refer to this farming method in Attack on Whispike (90G) to get strong and get a lot of abilities when starting a map. Once you do just begin the Alas Forest map with a bunch of abilities from the seeds and just don't move. The fire ability is really helpful because it will fire in the direction of the closest enemy. Be careful when selecting an ability when you level up so you don't accidentally move. Once 30 seconds hits the achievement will unlock.