Its very likely Spirebluff Canal was a death knell for these cards, but Boil and Choke seem like great ways to break certain counterspell-heavy decks
They copy themselves for each spell cast before it, so it's possible to cast enough spells to burn all your opponents with Grapeshot, or mill them all with Brain Freeze if you're able to cast a ton of spells in one turn (made easier with the Hullbreaker Horror combo)
Instant Color tag templates(None) Heritage Reclamation Choose one Destroy target artifact
It takes very little to make Neo Exdeath massive, which pairs nicely with cards like Rishkar's Expertise and Essence Harvest to make use of the huge body, and it does it all for a low, low mana value
The upside is that Boros Aggro does often play the lifegain package, so the creatures you get in the Challenger Deck will provide most of what you need to play the deck
Several of Mimikyu's Pokmon TCG cards involve its ability to negate opponent attacks of some kind