So in the last couple of expansions each class got two legendaries. Like in witchwood one villager and one monster or here in Boomsday 1 scientist and 1 spell. Sometimes the gimmick is a bit more special like the spells but I'd like to theorize about potential legendary gimmicks for upcoming expansions.
1. Di-class legendaries: each class gets 1 of their own legends an a legend to share with another class.This was each class gets 3 legendaries to work with.
2. Start of game legendaries: could help make a deck built around one card be more consistent. Maybe have a start of game hero card?
3. Destroy the enemy hero legendaries: legendaries that automatically win you the game if some sort of condition is met
4. Build-A-legend legendaries: Play a legendary minion and then discover aspects to make it powerful
Legendary crab to counter Druids. 3 mana 2/3: Destroy a Druid Hero. See, its balanced because its understatted. Sometimes wins you the game, or a completely dead card. In line with Blizzard’s design philosophy of ‘virtual rock paper scissors is fun!’