Itll only trigger once each turn, but that wont stop it triggering on other peoples turns, too
(2/5/2021) If an effect causes a creature with changeling to become a new creature type, it will be only that new creature type (unless the effect says "in addition" or similar)

Anduril, Narsil Reforged Aragorn, Hornburg Hero Legolas's Quick Reflexes Gimli's Reckless Might Isengard Unleashed Rohirrim Chargers IMMORTALIZE EPIC SCENESEach The Lord of the Rings: Tales of Middle-earth Scene Box contains 6 foil Borderless cards with art that combines to showcase one of the most epic scenes from The Lord of the Rings WITNESS ARAGORN AT HELMS DEEPPiece together these 6 Scene Cards to see Aragorn wielding his legendary blade, Andril, in the fight to defend Helms Deep against the attacking hordes PUT YOUR ART ON FULL DISPLAYWhile each Scene Card is a playable Magic card, this box also contains 6 Art Cards featuring the same art without any game text obscuring the view, allowing you to appreciate the full scene in all its glory on the included display easel EXPLORE WITH SET BOOSTERSDesigned for a fun pack-opening experience, get 3 Set Boosters full of more The Lord of the Rings-themed cards

The owner can recast it, but it's temporarily out of play, which can be a significant tempo setback for your opponent
Youre not guessing anymore
Thelonite Hermit: goes with anything dropping Saproling tokens, and then goes with anything that helps with counters on your creatures or gives you benefit because you have counters on your creatures