New trinkets have been datamined in Patch 10.2.5 which give the raid buff effects, Chaos Brand and Bloodlust.
Two raid buffs have been added to trinket effects in Patch 10.2.5: Chaos Brand and Bloodlust! It's unclear if this is placeholder but they could be awesome to fit in some of the gaps in raid composition at the cost of a player's trinket.
Alternatively, these could also be part of the Follower NPC Dungeon system coming in Patch 10.2.5.
A player will have to give up this trinket to gain the Chaos Brand effect which could be worth if you don't have a Demon Hunter in your group!
Instead of using Feral Hide Drums, this trinket would allow a player to get real lust, Blood of Mannoroth at the cost of a trinket.
It's not exactly a raid buff, but Ankh of Reincarnation is a neck that allows the wearer to resurrect.