Since there are some truly nasty Spell cards out there, its a good card to have ready, just in case
For example, if your opponents Active Pokmon has an Ability that says Any damage done to this Pokmon by attacks is reduced by 20 (after applying Weakness and Resistance)
Even though Vivi doesnt actually see a ton of Constructed play now that its banned in Standard, the damage it did while it was legal was outrageous
This expansion set, following the success of the first three (Base Set, Jungle, and Fossil), explores the question of what happens when Pokmon go bad
All of this said, if theres one big caveat with this deck, its that its impressive performance is based on a small sample size: it only made up 2.02% of tournament decks
Costing a mere 470 JPY (~US$3), a copy of an Unfair Stamp (Crimson Haze [SV5a] 053/066) card is highly affordable