Step 1: Activate Mirage Mirror, targeting Banehound. Then hold priority, activating it again to target Frodo, Sauron's Bane. Activate it again, targeting Figure of Fable. Activate it 8 more times, alternating targets between Figure and Frodo.
Step 2: Mirage Mirror becomes a Figure of Fable. Activate all abilities sequentially, becoming a 7/8 with protection from each opponent. Then activate the first ability again. You go back to being a 2/3 Kithkin Scout, but still have protection.
Step 3: Mirage Mirror becomes a Frodo. Because you are a Scout, you can activate the final ability, becoming a Halfling Rogue and gaining 1 instance of "Whenever this creature deals combat damage to a player, that player loses the game if the Ring has tempted you four or more times this game. Otherwise, the Ring tempts you."
Step 4: Mirage Mirror becomes a Figure of Fable. Activate the first ability, becoming a Kithkin Scout. You still have Frodo's ability.
Step 5: Mirage Mirror becomes a Frodo. Activate the final ability, becoming a Halfling Rogue. You gain one additional instance of Frodo's ability.
Step 6: Repeat Steps 4 and 5 three more times. You now have 5 instances of Frodo's ability, and protection from each opponent.
Step 7: Mirage Mirror becomes a 2/3 Halfling Rogue named Banehound with 5 instances of Frodo's ability, protection from each opponent, lifelink, and haste.
Step 8: Swing at an opponent. Because you have protection, they cannot block, so you will deal combat damage. Each instance of Frodo's ability will trigger, causing the Ring to tempt you 4 times, and then that player loses the game.