As a Legendary Spacecraft, The Seriema tutors for legendary creatures and, once fully stationed, transforms into a flying 5/5 that grants indestructible to all tapped legendary creatures you control
Various cards can add further power to the deck, such as the Goblin Anarchomancer, which makes green and red spells cheaper by one colourless mana, the Mage Slayer, which promises unblockable damage, or the Rhythm of the Wild enchantment, which protects your own creature spells from counterspells
(10/4/2019) If the creature would enter the battlefield with no +1/+1 counters on it, it enters with one +1/+1 counter on it
Lesson cards are actually back in Standard right now, appearing in Avatar: The Last Airbender
In decks capable of generating a lot of mana through rituals for example, this sounds very fun and powerful