I am posting this because at the beginning of this season, I was one of the people complaining about blast of discord and the scratch buff, etc. Now, after playing 100 matches at all levels, I think I can provide better feedback on the current state of pvp than before. That said, my findings surprised me.
Honorable mentions: Spring & Fall Champion's Weapons
The centaur queen is still the queen of pvp. No other companion has such a universally positive impact on a team regardless of class. A buckler can black fog, buff her agility with fan and her accuracy with toro, and charge her into the enemy line all in one turn. Privies and witches can put a massive absorb on her. She just has so many guaranteed hits and such good options for epics that she is usually the first target of an opponent.
4. Moo Robe
Even after a decent nerf, this item still makes the list because of the vicious charges. Pirates won't have to deal with nine of these summons, but five to six is still common. If your pet is out, it might absorb some of the blows, but otherwise, you can expect two of your units usually to lose their ability to hit things for a couple of turns.
3. Old Scratch
Let the saving grace of all witchdoctors flow! Scratch's three boosts to spell power provide more than just 2800 absorbs; they also keep characters with soul shroud safe without any shields, as they will drain about 700 health! Then, even if you manage to get them down to one hundred health, they will use jobu's embrace to gain all their health back while dealing a boatload of damage. Oh, and have fun with those big guns.
2. Time Warp
This guy surprised me as I didn't fully understand what it even did before this season. But after playing six matches against a buccaneer with this pet, I can say this: when the pet appears first round, your shields better appear too! The pet is guaranteed to trigger it if it joins combat then. All units get double speed, meaning a buccaneer player can fort himself first round instead of using highland and next turn wreak havoc alongside his companions. Furthermore, all those companions with relentless 2 now have relentless three. You can connect the dots yourself with a buckler/time warp combo. This is the flat out most offensive tool in the game right now.
1. Grants Relentless
Have you ever seen a buccaneer above hero without this? I haven't. The ability for a character to get relentless 2 is so overwhelming it's practically a requirement for bucks (assuming they have trained relentless of course). With a strength buff, these are almost guaranteed to proc against witches or musketeers, leading to the dreaded blade storm chains. It is no exaggeration to say that a character has a good chance to solo nausica and an even better one chance to take out scratch. This, after much deliberation, earns the title of the most overpowered thing in pvp.