Mercury’s Cloak (regular and dark version)
Once a highly favored item for damage-dealing champions, Assassins need durability to survive as long as possible in fights and were even rated at tier A, tier S. However, currently, both versions of this item hardly see much opportunity to appear.
While the regular version offers good defensive capabilities, the dark version provides defensive benefits throughout the match at the cost of reducing the champion’s maximum health by 20%. However, at this point, with so many traits providing healing, shields, and defenses, surviving in a fight for 10 seconds or longer means little if that champion lacks sufficient damage to take down opponents.

Due to the damage requirements, currently, aside from Viego, there aren’t many champions that will need to build Mercury’s Cloak (both regular and dark versions). In fact, if players aren’t careful, they could end up wasting resources and putting the champion with Mercury’s Cloak at risk of being overwhelmed late game.
Trap Claw
As previously mentioned, Trap Claw is one of the most unfortunate “disappearances” in Teamfight Tactics right now. At the beginning of the season, when the LeBlanc “chain god” meta was dominant, Trap Claw was considered the best item to counter this playstyle. However, when an item is only popular due to a specific meta, once that meta fades, the item will fall out of favor too. Trap Claw is such a case.
Not to mention its utility, even just considering the component items, both Belt and Gloves are more useful for other items like Warmog’s Armor, Infinity Edge… Furthermore, players would prioritize crafting the Vengeance Trap Claw instead, as it has proven useful from start to finish of the game. For these reasons, Trap Claw will continue to fade into obscurity.

Zz’Rot Portal (regular and dark version)
At the start of the season, Zz’Rot was considered one of the best items for frontline champions. Although it was primarily built as a “leftover item,” both Zz’Rot Portal and Zz’Rot Death Portal demonstrated their excellent utility. Another reason is that at that time, both Wooden Bow and Belt did not provide as much utility as they do now.
Currently, Zz’Rot Portal has been heavily nerfed and shares a similar fate to Trap Claw, as its component items are more useful when combined into other items. A multitude of reasons has led to Zz’Rot Portal and Zz’Rot Death Portal becoming less favored among TFT players than they were before.
