Slayer

Western Wastes is what I've got listed. You might be able to swing through ToV and Crystallos as well though

The quest giver dragons in Field of Scale (SoD) count. There's like...6 or 7...and repop in around 10 min or so. Don't worry about the little armies around them...they won't attack (usually).

To the Devs,

Please PLEASE consider adding brooms from HoT expansions for the slayer achievement: "Witch Mount".
This achievement requires 50 broom minions killed, and as of now, ONLY Arx Mentis brooms count towards this achievement, making it a huge timesink for those of us who play multiple toons on different accounts each be required to do the huge line of progression quests and missions required to get flagged for Arx Mentis. I've been enjoying the slayer changes so far and working towards Megadeath, but things like this need to be reconsidered.

Thank you!

Witch Mount is an optional step, just skip it.

Wow you are right, thank you. I saw it under Skill slayer achievement tab and so figured it would be a part of the Progressive achievement (it is not).

For less advanced characters/servers, a good spot for swordfishmermaid is the room just below Undertow in Kedge Keep where the seahorses start. There a couple handfuls of level 4 fish that spawn very fast and you can stay in the corner safe from anything higher level.

I did that one in Rivervale. There is a pond that respawns ~4x fish every 6-12s. Simply take a bard with the level 2 AE dot and park him in the water singing.

Actually, the best place for True Dragons is The Breeding Grounds. All of the winged 4 legged ones are considered true dragons. Also get a good number of drakes and such as well. They are also fairly close together rather than all spread out.

This is where I ended up getting it done, thanks. Not the fastest achievement still but I believe breeding grounds is the fastest spot if you can actively clear the zone of the big ones faster than the respawn in the other options.

Rivervale Pond was amazing for fish.

Ocean of Tears has an insane amount of Goblins on several different islands in the zone. There is also the Aviak Island for Zookeeper, you'll be waiting on respawns but some of the ones on the shore respawn faster than the rest. Even better if you're doing Goblins at the same time you can just hop between islands. I did notice there are a lot of Wood Elves in OoT also, NOTE they are on Kelethin faction, but I didn't need them by the time I discovered them so didn't mess with them.

I couldn't figure out the OP's location for the Cubes, I ended up doing this in Gunthak and Dulak on Luggalds. Not tons of them in Gunthak but they are lower level thus die faster, in Dulak basically every single mob past the fake wall counts for this achievement but they're like 10 levels higher I think.

(Mischief server.)