Today's update added missions for completing story quests for Episode 5 chapter 4 onwards. Since we previously had chapters 4 and 5, many of those missions arrived pre-completed.
In addition to giving 200 Rising Weapons Badge 4 and 50 Unique Weapons badge, the pre-completed missions (for those of us who were on top of story) gave us the Back and Arms Phobos units with 6 augments. I expect a mission for one of the chapter 6 story quests will give the accompanying Legs unit.
These are definitely new budget unit sets. Thanks to their base stats being almost the highest in the game at the moment and the starting augments being even better than the buster medal exchange Ivlidas, they are the go-to for anyone that hasn't invested in their units for a while. And for anyone that has, they'll make a great upgrade for low-cost alt characters.
Phobos units' primary drawback is that they give no PP at a time when most other 12★ units give around 10. The better augments on the pre-affixed version compared to other options reduces that gap, but you're still looking at around 21 PP loss for 120 Pwr gain compared to the buster medal exchange Ivlidas upgraded to Cleasis.
For anyone that doesn't want to invest in augment affixing or transferring, the three primary options for pre-affixed late-game units are the buster metal exchange Ivlidas upgraded to Cleasis by Zig, the Starquake/Trailblazer units available from Zig, or these. The first option requires grinding a handful of buster medals (not too bad) and 300 Cleasis Booster (not too good). The second requires 300 Void Erebite Fragments (apparently these are limited to a new urgent quest; I don't know their drop rate), and the third just needs story progress.
So even if a player that's fallen behind needs PP, these pre-affixed Phobos units being easily the easiest upgrade means they could still be useful as a stopgap while setting up one of the other options for PP.