The ability triggers when he dies, and youre choosing to change zone when he is then put into exile as part of the ability resolving
6 Mana Vault By Christine Choi - $125.73 Double Masters 2022 (2X2) #560 Another mana vault from the Double Masters 2022
Admittedly, Pokmon TCG Pocket isnt the best game for creative deckbuilding at the moment due to the presence of so many meta-defining cards that seem designed to pair perfectly with specific combinations (i.e., Mewtwo ex and Gardevoir or Moltres ex and Charizard ex), alongside the fact that there are eight or so cards that basically every deck should include
The card and events will come to other regions, with more info to come
Okay, you still need to exile six cards from your graveyard and it can be very bad in multiples if you need to exile six more cards, but what if you got to manifest it, and flip it later for just 3 mana
It punishes sacrifice effects by stealing what your opponents give up, and it forces those sacrifices regularly with annihilator 2