Having this in your deck makes every other play safer , because you can commit your mana fully and still have an answer
TCG Pocket launched without the ability to do so despite the name of the game and when it did debut, it came with another new currency and restrictive rules around what cards you could trade, enticing you to spend more real-world money on packs, as gacha games are wont to do
Promos, common cards, whatever
Lier, Disciple of the Drowned stops spells from being countered
If you can survive with even ten HP, then you get a free turn to potentially heal, set up a follow-up or even knock out your foe instead
"OP08-067 Charlotte Pudding" is a crucial card for this deck, as it helps replenish the DON