Legendary cards require no specific orbs, are very power-expensive and you can only have one unit of its kind in play at a time (including allies and enemies). There are a total of 23 Legendary cards in the game. None of these are Tier One cards.
Tier Two
Buildings
| Dark Crystal | Earth Crystal | Flame Crystal | Ice Crystal |
Creatures
| Easter Egg Promo | Moon | Rogan Kayle | Rogan Kayle Promo | Viridya | Viridya Promo |
Tier Three
Buildings
| Amii Monument | The Incredible Mo |
Creatures
| Brannoc | Lord Cyrian Promo | Mo | Mo Promo | QueekQueek | Santa Claus Promo |
Spells
| Curse Orb | Curse Well |
Tier Four
Creatures
| Jorne | Ravenheart | Ravenheart Promo |