Whats on This List Interestingly, many of the energy cards on this list are from the 25th Anniversary Creatures Corporate History Deck that was only given out to Pokemon illustrators and certain employees at the company
Oct 2021EN Celebrations Umbreon reprinted in the Classic Collection, and a brand-new Greninja (SWSH144) included in Celebrations Elite Trainer Boxes
Thankfully this will trigger whenever the 10th is put on it, and it's not restricted to a certain timing
(Whenever it attacks, for each opponent other than defending player, you may put a token that's a copy of this creature onto the battlefield tapped and attacking that player or a planeswalker they control
Like Opal, it can also be addressed quite cleanly from the sideboard
Shuffle 2 of your "Blackwing" monsters (1 Tuner and 1 non-Tuner) that are banished and/or in your GY into the Deck/Extra Deck