General

@appall: Speed shot clears the infrequent top platform mobs when ever necessary, I always have top platform clear. As soon as a mob or two spawn up there I time them and speed shot em.

@yunioracosta: I strongly disagree. we can't hit top platform, and Bowmaster is wayy better for sdh

thunder breaker - mobility, mobbing, and aggressiveness
boring at first couple of jobs, but becomes insanely fun once you can utilize all skills

Mechanic

edit: mobbing+aggressiveness = hayato or kanna

Blaze Wizard is the choice for an aggressive mobber since it completely destroys Second Drill Hall (a horizontal map) which is where you train at during endgame stages. Its main attacking skill orbital flame has very good horizontal range and it you can continually spam it until the entire map is covered by orbs.

I'd suggest blaze wizard, but my second choice would probably be Phantom and/or Luminous (latter excels at nonlinear maps)

If you can OHKO mobs then Angelic Buster are pretty good with mobbing too. Justice Hammer and Celestial Roars have fairly large vertical hit range, so you can hit mobs that are above you. With Soul Seeker Expert on you can even get to the monster that's far away from you.

Finally with Grappling Heart and Double Flash Jump ABs can move around very quickly.

A class that is both mobile and great at mobbing/training overall? I believe that class is called a 'Hayato'. Well, Phantom with Cannon Bazooka is far easier to play and Luminous is overpowered at mobbing, but Hayato is far more engaging and has an insane variety of skills. Thunder Breaker and Zero (unavailable for creation, but hopefully you made one when you had the chance) are also valid choices in this aspect.

Mechanics; they mobility is fairly good (thanks to the portals) and their mobbing is fairly overpowered even without their summons, so with the summons... Well, you pretty much own the entire map. The downside being their playstyle might be 'boring' or 'passive' to some, since you actually have to micro manage your summons while trying to move around the map in the most optimal way possible (although there are maps where you can simply nuke everythng left and right, of course)

Blaze Wizards have the great mobbing skills mages generally have but instead of teleport they have access to the Cygnus Knights flash jump ('Elemental Shift', I believe? The best flash jump in the game, anyways) as well a 'teleport back to the marked spot' and a basic attack skill (Orbital Flames) that can be used in any of the four cardinal directions. That being said, they are just an 'OK' mobbing class compared to other mages (which are mobbing powerhouses, anyways), but excel at mobility

If you want to play another Thief, although you already main one, Night Lord. Fairly similar to Phantom himself, specially considering Phantom can actually steal Showdown Challenge if they really wanted and both classes have homing projectiles, so overall, if you want to try something 'different', stay away from Thieves. They are either not great at mobbing or Phantom can mimic their advantages anyways.

Finally, most mages are good mobbers, although fairly 'slow' (great at dodging, however, thanks to telecasting), not that you need to be fast when you have a variety of skills that allows you to blast everything in sight. Of course, you have classes like Luminous, who are great at training and mobbing at almost ANY situation... But can get REALLY boring very quickly since you pretty much don't even have to pay attention to the game.

Marksman at 4th job have one of the best mobbing skills. I wish I had a video to show you but at SDH with the ability to one hit you can wipe out the entire map with 2 key strokes.

Mechanics
Lumis