Gandalf the White, for example, is designed to mainly care about legends, but he can also break the famous artifact Isochron Scepter, as noted in this Reddit thread where users recognized the potential that Gandalf's ability adds to the Isochron Scepter.

Source: https://www.cbr.com/mtg-lotr-gandalf-ability-break-isochron-scepter/

It's a sizeable 4/5 Avatar Wizard with flash, and Gandalf the White allows the player to cast legendary spells and artifacts with flash as well, which can take the opponent by total surprise.

Source: https://www.cbr.com/best-mtgs-tales-of-middle-earth-cards/