She has no plus ability, so at first you might think she has no way to hit her ultimate
Key Mouse X EARTH Level 1 [ Beast / TunerEffect ] ATK 100 DEF 100 When this card is destroyed by battle and sent to the Graveyard, you can add 1 Level 3 or lower Beast-Type monster from your Deck to your hand
Its likely Enchanted Simba didnt get picked up on because Enchanted cards were announced very late

Brigette Full Art - 161/162 - BREAKthrough - Holo Out of Stock Chesnaught BREAK - 12/162 - BREAKthrough Out of Stock Florges BREAK - 104/162 - BREAKthrough Out of Stock Glalie EX - 34/162 - BREAKthrough - Holo Out of Stock Glalie EX Full Art - 155/162 - BREAKthrough - Holo Out of Stock Houndoom EX - 21/162 - BREAKthrough - Holo Out of Stock Houndoom EX Full Art - 153/162 - BREAKthrough - Holo Out of Stock M Glalie EX - 35/162 - BREAKthrough - Holo Out of Stock M Glalie EX Full Art - 156/162 - BREAKthrough - Holo Near Mint - 1 In Stock M Houndoom EX - 22/162 - BREAKthrough - Holo Out of Stock M Mewtwo EX - 63/162 - BREAKthrough - Holo Out of Stock M Mewtwo EX - 64/162 - BREAKthrough - Holo Out of Stock M Mewtwo EX Full Art - 159/162 - BREAKthrough - Holo Out of Stock M Mewtwo EX Full Art - 160/162 - BREAKthrough - Holo Out of Stock Marowak BREAK - 79/162 - BREAKthrough Out of Stock Mewtwo EX - 61/162 - BREAKthrough - Holo Out of Stock Mewtwo EX - 62/162 - BREAKthrough - Holo Out of Stock Mewtwo EX Full Art - 157/162 - BREAKthrough - Holo Out of Stock Mewtwo EX Full Art - 158/162 - BREAKthrough - Holo Out of Stock Noivern BREAK - 113/162 - BREAKthrough Out of Stock Raichu BREAK - 50/162 - BREAKthrough Out of Stock Zoroark BREAK - 92/162 - BREAKthrough Out of Stock

As to when to stop torturing our aquatic friend, once you average turn 3 kills over a reasonably-sized number of games (or simply once you feel comfortable you wont miss these plays when also having to consider your opponents options), you should be ready to move on to playing actual games
Once again, while theres no denying the strength of Sword of Feast and Famine, its current price point is surprising