My first pick would be combat tricks
Other valuable 1st Edition holos from the set include Dark Dragonite ($4,000 to $6,000 in PSA 10), Dark Blastoise ($5,000 to $8,000), and the Dark Raichu secret rare
Morbid At the beginning of your end step, if a creature died this turn, populate
That plays quite well in a Voltron-style build where you make your Tanazir bigger and also makes your Hydra and similar X creatures bigger as their base is normally 0/0 so you get a +4/+4 effect to them without shifting the power of the founder of the Quandrix School
The only standout here is Mew ex, which still sees play as a free pivot option and as a means to draw cards in aggressive decks such as Raging Bolt
That flavor pushed this card to white and meant both the ETB effect and the prize for defeating the battle needed a protective element to it