Last block, we experienced some new events at each set's prerelease, launch weekend, and Game Day. The Hero's Path events - get hero cards, solve puzzles, play against automated Challenge Deck - appeared to be a test run for a more immersive (and more gimmicky, but also completely optional) future for Magic events.
Enter the Magic 2015 prerelease. The Hero's Path was successful enough to repeat the venture, only this time there's no luxury of a real story or a long build-up. So we skip straight to the action - a contest pitting one Sealed deck against a player who has no deck at all and pilots the scariest planeswalker card of all time. The oversized "boss Garruk" has to have decisions made for him by a real person and looks like this, in every prerelease pack:
Garruk the Slayer
Planeswalker - Garruk (No Rarity)
0: Put a 2/2 green Wolf creature token onto the battlefield.
+4: Target Wolf creature gets +1/+0 and gains deathtouch until end of turn.
-10: Destroy target creature. Put loyalty counters on Garruk the Slayer equal to that creature's toughness.
-25: Destroy all creatures Garruk the Slayer doesn't control.
The expected fair-play rules are in place: No removing Garruk except by damage, and the only way he can lose is by having all his loyalty taken away. He has a rather straightforward playstyle: Controlly, creature kill happy, clearing the board for a decidedly non-evasive army. Either you outrace Garruk, or you pack removal proofing. There's no prize for winning, but taking a selfie with the larger than life prerelease Garruk standee could win you the cheesiest piece of Magic swag ever: A Nerf version of the big man's execution axe. What this all means for Garruk being in the set proper with a real card is unknown, but it still seems more than likely he'll appear, and you might summon him to battle... himself.