So I was bored today, as many Destiny 2 players are, and I just felt like testing out new weapon combos and not so popular exotics. I ended up launching a standard raid and sitting in the Castellum for about an hour and thought that it would be a great space for a horde mode. Just change the coding a bit to accommodate to less guardians (lets say 1-3) and launch a Castellum Horde Challenge in the third slot on the raid menu. It could be just a simple live for as long as you can or throw a few tasks to complete through each round. Bungie could even throw in a challenge card that lets players mod the experience, like adding in a vex themed random event in the horde mode (tying it to the Raid Lair). Throw competitive scoring between the contestants and you have an interesting addition to keep some players invested. Loot can be done like the Challenge of Elders (not a popular mode but was fun and had a lot of potential) you may even earn some Calus tokens. Bring it to the weekly milestones and it can be a highly sought after commodity, maybe a guaranteed masterworks bundle as a reward?