Smoke Grenade of the Thief was released in 2005 as a part of Legacy of Darkness. It was unremarkable for years, but in December 2020 the card was banned. This brings up the question “Why is Smoke Grenade of the Thief banned?”
What does Smoke Grenade of the Thief do?
Smoke Grenade of the Thief is an equip spell. When this card is destroyed by a card effect while equipped to a monster: Look at your opponent’s hand and discard 1 card from their hand. The effect of looking at the hand is good, and choosing one to discard is even better. However, the effect is really hard to get to work. For this reason the card saw little to no play for a very long time.
However, the problem is that one player has to destroy the card in order for the effect to go off. Your opponent won’t activate it by choice. However, you are also able to MST the card. Despite this, the card was ignored because it is a card that is unnecessary and rarely gets activated.
The card became usable
Infernoble Knights was a deck that was pretty good in 2020, and it was the deck that exposed that maybe Smoke Grenade of the Thief was poorly designed. The deck had a synchro monster named Infernoble Knight Emperor Charles that was able to exploit the card. This card lets you destroy a card on the field. However, You can equip 1 Equip Spell from your hand or GY to this card. This means that you can reliably use Smoke Grenade of the Thief repeatedly. This was likely an unintended combo, but one that happened.
Due to circumstances not a lot of events happened in 2020, so the deck didn’t dominate in tournaments to my knowledge. The combo was just incredibly annoying, and it is anti-fun.
Can it be unbanned?
Nope. I think the damage has been done, and the card has been exposed. Viewing into your opponents hard is really, really good. However, this is taken over the edge by the discard one effect. I think having this card in the game limits the creativity of designers.
If you are interested in more cards that look into your opponent’s hand then I suggest this article on Confiscation.