Historically blue has outsourced most of its finishers in counter based control decks but more recently seems not to need to so much
Outside of introducing new cards, Shadows in Valhalla has some amazing competitive reprints for players, including: Mermail Abyssmegalo, Invoked Mechaba, Windwitch Ice Bell, Twin Twisters, Shaddoll Fusion, Gem-Knight Seraphinite, Aleister the Invoker, El Shaddoll Winda, Cyberdark Impact, and, the most important reprint, Ash Blossom & Joyous Spring
Fortunately, there is one Stage 1 Pokmon that allowed this attack to be significantly more efficient, and Metang was a crucial part of these incredible meta decks
Prisma Light Switch Adapted The Prisma Light puts on an awesome light show
If you need to protect your other Aqua monsters (specially Toad)