Keep in mind, this is not my idea, but from a friend that told me this idea a few months ago.
Original Idea: PumpkinsGT
Okay so… if you use like a Completely FULL SET then
you would get like a Unique Buff of Extra Armor added to
the Armor you already have from the Set.
Example:
If you wear all the Paladin’s Set peices, it would give you an Unique Buff with Armor or maybe even Damage, or Critical or something else.
Very good idea, this will make underrated part of a set be more useful…
aku suka kura-kura :vvvvvvv
Great idea. This would encourage players to collect an entire set instead of only a few items people generally like. It would also make PVP more interesting since you can choose what kind of set you want to get a nice buff.
On the flipside this might discourage players collecting sets that don’t have a “good” buff, which might lead to some sets not getting any praise at all.
Great idea. This would make PVP and PVE so much different.
should be in #site-feedback:game-suggestions
but i support this because i only have 40 armor, goaling for 50+ and this is very useful!
Wow imagine the frostborn set but with a buff that makes it actually viable for general use rather than having subpar defense stats when compared to far cheaper pieces of equipment.
This might come in the January update.
Ahhhhh Terraria feature 
I haven’t played Terraria in like forever, even though i have it.
But i barely remember the game, since i played it back in 2011.
I don’t actually know that the game had something similar to this idea.
I don’t think PumpkinsGT have played the game at all.
I’m pretty sure he came up with the idea himself. 
It’s definitely not a unique feature to Terraria, but Terraria was one of 4-5 big influences on the creation of pixel worlds, just made sense to mention. It’s a good idea to add reguardless!