Capturing the growth of a heroic journey and its trials with a gradually increasing mana investment is lovely, and its become the template for interesting creatures like Surge Engine
Marcy: Brynhildr is an Eidolon (another word often used for Summon, all of which are essentially a term for a category referred to as "Avatars") in FFXIII, where she appears as a motorcycle ridden by Sazh, and transforms into the form seen here when summoned
All of these cards can be cast for their front side casting cost, or the alternate More Than Meets The Eye cost, to have it enter the battlefield converted on its back side, similar to transforming effects found on many werewolf cards
Wizards has and may continue to print special versions of cards not meant for regular gameplay, like oversized cards
Conspire Conspire is basically a replicate variant from Shadowmoor ,where you can tap two untapped creatures to make another copy of the spell