You can identify what rarity your Lorcana card is by looking at the rarity symbol at the bottom of the card, in the centre of its border
That said, flashing in Weeping Angel provides a clean answer to even the largest and most hexproof or indestructible creatures
Two immediate options that come to mind are Jodah, Archmage Eternal, which basically lets you cast this for WUBRG and then net yourself 5 mana to help cast the spells you reveal, and Mizzix of the Izmagnus, which can cast this 10cmc spell for as low as RRR
Arthur attacks, and you happen to put Bloodthirster in play
Once per each turn when you activate ninjutsu, you can look at the top three cards of your deck, take one, and put the other two at the bottom
The other two cards in Secret Lair AoS arent too special, but their Warhammer inspirations are great