HELP! 12.5k Au and 25k WSP. Don't know what to buy!

I would buy a Fury and a Galahad along with 2 more orkans.
Replce the Zeus Carnage for a Trident Fury or Trident Zeus Trident Fury (that build is weaker but fun)
I would replace the Plasma Griffin with a Plasma Galahad.
The Dash bot will probably cost event currency so I think you can forget about it.
The moon map heavily favors the Aphid Orkan Griffin. If I were you, I would consider buying 2 Aphids.

Even if they dont perfom as well on the new map there are still plenty of other maps that fit them well.

I am not going to advise on any speculative end-game meta (I am neither qualified to nor especially interested in doing so) my advice comprises subjective choices based on effective fun purchases for now.

If you want to play without a beacon runner:

Get 2 more Orkans - 2400Au
Buy a Galahad, equip it with plasma - 2500Au

If you want to play with a beacon runner:

Buy a Gareth. Now. 1250Au


And finally (and I know many do not agree and can give chapter and verse on top tier)...

... after opening the 4th slot my first Au purchase was a Rogatka - 2500Au. This predated the BritBots. I love my Rog, I have never regretted the purchase; I still pilot it in at least 80% of matches. It is fun! At mid-levels a Taranasaurus Rog (plasma) is a beast. Where I play, mostly level 9-10 'bots, weapons 10-11, a Rog with twin Orkans can, with skill or luck (or both) be devastating to BritBots as well as most others. My Rog loves Gareths. They're yummy.

If deferred gratification really isn't your thing also get a Gepard - 1200Au - slap those three Aphids on it and go and have a play. Still an occasional guilty pleasure of mine.

I've found that the Carnage s mobility kinda makes up for the Fury s 3rd heavy weapon. Thoughts?

Nope. Ever since I bought my Fury, my Carage stayed strictly thunders.

I like your current hangar quite a lot. I would look to replacing the RDB Griffin probably first. I would not buy two bots at once, that just bogs down your upgrade path quite painfully.

I personally subscribe to another posters advice from here. I try to have 2 splash, 2 energy and one mid range support bot in my hangar. The mid range bot can be either, and I like to muck about with my mid range (though lately it has consistently been a Trident Carnage).

Seeing as you have excellent bots in a death button griffin and plasma griffin, consider those two slots adequately covered. One energy, one splash. Check.

I would take the ancile off the Leo, and put it onto a spanky new Lancelot. Throw two orkans on that bad boy and go rip someone a new orifice. Splash bot. Serious check. Remove the RDB to make room.

Ah the Leo. Short term I would keep it in the hangar. We have new bots coming (maybe?) and damned if everyone isn't running a  Thunder Pinata Leo just to pad their damage. A Thunder Pinata Leo almost always does its own weight in damage. Bit of splash, but of kinetic. Its a bit of a round peg in a square hole, but don't worry you can bash it in there with a Leo.

And the Zeus Carnage. I think I would honestly leave it as is, but do as I did and have two tridents to trade out on it. Run one, run the other. Have some fun with it. Can be splash, or energy, or both!

Any other thoughts guys?

It is deadly, but the use of it is rather limited as there are lots of shield bots around and cover is used a lot. 
Trident Fury is overpowered. 

I second this, with one minor correction: Not "almost" every map... EVERY map.

Swap your plasma Griffin for a Plasmahad and you will never look back!

I sometimes find the Galahad a bit useless in maps like Dead City where ambushing is favored over continuous exchanges of fire. 

It's just that my Galahad plays are not so good on Dead City as compared to other maps like Canyon and Yamateau.

I run 2 Plasma Galahads in my hangar.