In Urza's Saga , they showed up on Wizard Mentor
(-8: You get an emblem with "Whenever a creature enters the battlefield under your control, you may have it fight target creature." Then put three 8/8 blue Octopus creature tokens onto the battlefield under your control.) I like the ultimate for the Theros block Kiora better
At best, it significantly disrupts one of a couple very specific types of strategies, and you could do that just as easily with a more all-purpose board wipe capable of slowing down all your opponents at once
What's findable now: Standard ETBs have restocked at various retailers but prices remain elevated above MSRP
Hakbal allows you to both out-resource and overpower your opponents with ease, building up to a winning play in a scant few turns
If you discard a Fighting Energy card in this way, this attack does 40 damage plus 20 more damage.