This is actually one of the hardest waves in the Holo-Sim. All Holo-Sim waves are random so keep playing for this to show up.
This wave will always take place on the right side of the map with a crashed ship and hostages that need to be protected for a set amount of time. Madam Hydra with sho up with an unending amount of Hydra agents during the time period.
You can start to attack her directly but as soon as she takes a certain percentage of health she will put up an invulnerability shield and spawn Elite Hydra agents. Kill the agents to drop her shield and continue attacking her until she bubbles again or is dead.
Once you kill her you must continue to protect the hostages until the time limit is up to get the bonus reward box.