Similar to landfall but for creatures, alliance is an ability that triggers whenever a creature enters the battlefield
And the only way to summon that card is if Yubel is destroyed by anything other than its own effect
4 John Silver, Alien Pirate There are a lot of good things to say about John Silver, Alien Pirate
Source: Wizards of the Coast Magic: The Gathering Video Game(s) Magic: The Gathering, Magic: The Gathering Arena
Youll notice that we remove cards like Mystical Space Typhoon, Heavy Storm, Card Trooper, Plaguespreader Zombie, Threatening Roar, and the one Lyla (as previously mentioned) in favor of cards such as 2x Imperial Iron Wall, 2x Fossil Dyna Pachycephalo, Lightning Vortex, and Book of Moon
The other boss monster within the same structure is Red-Eyes Zombie Necro Dragon