When activated this will bring a squad of Stormtrooper infantry from an off-map point. Stormtroopers are similar to Grenadiers but have more health, take up more population cap, have higher upkeep cost, and take longer to reinforce. The trade off is that Stormtroopers come with the ability to camouflage themselves just like snipers, making them a great assault unit.
Stormtroopers also have an option to upgrade themselves with Panzerschrecks or with STG 44 assault rifles. Each cost 75 munitions and give you one weapon upgrade per purchase (with a max of 2 per squad). However, to get access to those upgrades you need to have Tier 2 for Panzerschrecks and Tier 3 researched to have access for MP44s. In addition, the Tier 3 tech provides all Stormtrooper squads with the bundled Grenade ability.