Prevent all combat damage that would be dealt this turn by non-Spider creatures
Be on the lookout in the coming weeks for any other bonus card reveals
The first wants you to play as many creatures with two power or less as possible, the second creates its own 1/1s to trigger Enduring Innocence
As is becoming common for MTGs major releases, an extra card with a set-specific art treatment will be packaged in every Wilds of Eldraine booster pack
Apparently it will feature "fan-favorite characters, including some double-faced cards, and planeswalkers"

0002_MTGTLA_BBTheme: Aang Tutorial Theme Card 8 Plains Aardvark Sloth Razor Rings Path to Redemption Appa, Aang's Companion Sledding Otter-Penguin Aang, Air Nomad Katara, Heroic Healer Momo, Rambunctious Rascal Aang's Defense Sokka, Wolf Coves Protector Tundra Wall Wolf Cove Villager 0008_MTGTLA_BBTheme: Zuko Tutorial Theme Card Dragon Moose Explosive Shot Run Amok Fire Nation's Conquest Komodo Rhino Zuko, Avatar Hunter Zhao, the Seething Flame Iroh, Firebending Instructor Zuko's Offense Fire Nation Soldier 8 Mountain Capital Guard Warship Scout 0001_MTGTLA_BBTheme: Allies Theme Card Kyoshi Warrior Guard Jeong Jeongs Deserters Glider Kids Avatar Enthusiasts Allied Teamwork Aang, the Last Airbender Suki, Kyoshi Warrior Rabaroo Troop Master Piandao Mechanical Glider Path to Redemption Airbending Lesson Thriving Heath 7 Plains 0004_MTGTLA_BBTheme: Waterbending Theme Card Flying Dolphin-Fish Otter-Penguin Katara, Bending Prodigy Sokka, Lateral Strategist Cat-Owl Flexible Waterbender Giant Koi The Terror of Serpent's Pass Watery Grasp Bender's Waterskin Deny Entry Waterbending Lesson Thriving Isle 7 Island 0003_MTGTLA_BBTheme: Spells Theme Card First-Time Flyer Master Pakku Rowdy Snowballers Iguana Parrot Turtle-Seals Geyser Leaper Serpent of the Pass Barrels of Blasting Jelly Abandon Attachments It'll Quench Ya
