Despite their appearance as old men, the Istari are far from frail beings. They possess magical powers greater than those of the Elves, using staffs to channel their power in times of need. Their powers include casting illusions, summoning lightning and firebolts, healing others, telekinesis, and even controlling the minds of other beings. Their staffs weren’t required for all magic use, but their powers do have limits without them. However, despite all of these fantastic abilities, the Istari were encouraged to only use their powers in times of crisis, instead relying on their intelligence and wisdom to overcome most challenges.
Physical combat was also only to be used as a last resort by the Istari, even though they were incredibly skilled at hand-to-hand combat and weaponry. Gandalf was one of the few wizards to engage regularly in combat and fought alongside the Elves, Men, Dwarves, and Hobbits in many of the great battles of Middle-earth.
Even though the Istari can be killed, as evidenced by Gandalf’s run-in with a Balrog in The Fellowship of the Ring, they can also be brought back to life by the Valar (God-like immortal beings that are said to rule over Middle-earth). Gandalf was resurrected because the Istar’s task – helping the people of Middle-earth stop Sauron – was not yet complete.
It’s unclear when exactly the Istar came to Middle-earth. In Unfinished Tales, Tolkien wrote that the Istar didn’t appear in Middle-earth until the Third Age, but in The Peoples of Middle-earth, he changed his mind and suggested the Blue Wizards began their mission in the Second Age after the forging of the One Ring. With the Stranger’s reveal in the season finale, The Rings of Power seems to be borrowing from the latter origin story.
While it’s not yet confirmed which of the five Istar the Stranger is, his peculiar arrival inside a meteor and his unique powers make more sense now (Gandalf is no stranger to dramatic entrances after all), and it will be interesting to see what he and Nori discover about his identity in season 2.