It destroys all creatures with power 4 or greater , which often wipes the biggest threats while leaving your own token board intact
For those of you who want the explanation, here you go
Velvet pouch (soft, elegant, rune-inspired design)
C Common Thunder Hand X LIGHT Level 4 [ ThunderEffect ] ATK 1600 DEF 1600 If a face-up monster(s) you control with 1600 original ATK or DEF is destroyed by battle or an opponent's card effect and sent to the GY, while this card is in your hand or GY: You can Special Summon this card (but banish it when it leaves the field), and if you do, destroy 1 card your opponent controls
Theres also the inherent benefit of deck-thinning, though from a statistical standpoint its not exactly clear that deck-thinning is all that fruitful in a game of Commander
Pull rate from Regular Packs: 2.38% The estimated pull rate for Slowpoke (Wisdom of Sea and Sky) from a Regular Pack is approximately 2.38%, meaning you might need to open around 43 Regular Packs to obtain it
