So I’m planning my first Spelljamer campaign as a GM (been GMing in general for 20ish years) and I’m using my own setting. One thing I want to incorporate is a Astral guardian type that draws inspiration from Power Rangers, The Green Lantern Corp and the Cosmo Knights from RIFTS.

what I settled on is artifact “morphers” that are sentient (not so much to take over a person like a regular intelligent item but sentient enough to determine if a person is worthy of the power.

These items will have level/growth (hitting level is not enough, hero must show growth as a source of good) unlockables. Rough Example:

level 1: Summon Weightless dragon Plate (attuned is automatically proficient with armor if not normally proficient with heavy Armor) that is immune to element associated with dragon type. Strength while morphed is set to 21 unless already higher. Armor/Morpher automatically translates languages for attuned (understanding only not speaking it)

level 5: Astral Armor can create it own SpellJammer field and allows the Knight to travel the Astral sea without a ship. Knight also gains a flight speed double the walking speed.

level 10: Automatically succeed on concentration checks one time a day per proficiency bonus. 

level 15: Immunity to Radiant Damage and heals for half damage would have taken if radiant. 

level 20: undecided on a good capstone ability for a 20th paragon of good

Now the ways I plan to keep these powers in check is they will have rules similar to a Paladin oath:

1) Must be used to face an appropriate threat (example hero wouldn’t be able to morph to stop a Goblin raid but say an adult dragon would allow them.)

2) Can’t be used for personal gain. Period. Selfish acts while morphed will automatically transform back to normal. Evil acts will cause unatunnment and departure.

3) Must keep identity as an Astral Talon a secret. This is a secret order or Knight working behind the scenes in plain view for the betterment of the cosmos. 

Violating any of these tenants (more to come) will stop allowing a talon from accessing any unlocked abilities until atonement takes place, sans evil acts that causes loss of power. However a departed morpher can be captured and corrupted allowing for evil talons (in order to corrupt a equal or greater power to Bahamut only evil must corrupt it)

If you are unfamiliar with the Mythical Odesseys of Theros book, you may want to look into how the artifacts and their "piety" system work to influence your design mechanically. The piety system, as a whole, is a great way to simulate forwarding the goals and beliefs of an intergalactic power centered around a sentai-like system of space cops. The more your players work to push the organizations narrative, the more power they will unlock.

capsotne ability, capstone ability, what could it be... it is armor. hmmmmmmmmm. immune to radient and (cold/acid/fire/poison/lightning). what if for a capstone, OHHHHHH

                            Zodar.

                                                                                                  Boo's astral menagerie

                                          last page

                                                                                                                                                          for a capstone, they can cast Wish. no components, no chance of failure, but it has to be approved by the armor. casting wish in this way causes the armor and knight to both be destroyed