This creature reads: Whenever an opponent casts a spell with mana value 3 or less, Scalding Viper deals 1 damage to that player. Basically, if youre against a deck that purposefully keeps their cards cheap, a single copy of this card could end them
Ultimately, thanks to being an iconic character who can actually see play, its no surprise that The Master, Transcendent is popular
Every form of disruption printed in the last decade has been great against Living End
Defensive phase-outs like Teferis Protection also allow creatures to dodge boardwipes, edicts and other non-targeted removal, where many flicker effects simply return them to the battlefield in time to perish by the next spell you had been responding to on the stack
Its a good way to push some unavoidable damage on your opponents, but it could definitely be better