Gunners after da patch.

20 Double Fire
10 Dash
20 Quick Motion
11 Backflip Kick

------------------

20 Mastery
10 Critical Gun
20 Invisible Shot
10 Float
20 Backstep Shot
20 Booster

20 Fake Shot / 1 Grenade
or
20 Grenade / 1 Fake Shot

------------------

20 Triple Fire
20 Cooling Effect
30 Octopus
20 Homing
20 Lucky Dice
20 Flamethrower
21 Gaviota

------------------

10 Battleship
30 Battleship Cannon
30 Battleship Torpedo
10 Counter Attack
20 Advanced Homing
20 Support Octopus
30 Air Strike
30 Rapid Fire
30 Elemental Boost
30 Maple Hero
3 ETC Points

Laik dat.

10 Battleship
30 Battleship Cannon
30 Battleship Torpedo
10 Counter Attack
20 Bullseye
20 Wrath of the Octopi
30 Aerial Strike
30 Elemental Boost
29 Maple Warrior
28 Rapid Fire
5 Hero's Will
1 Hypnotize

That's what I'm going to do for 4th job. Since ship's cooldown is only 30 seconds, Rapid Fire is even less useful. I'll leave it at 28 and get some Paladin to max it olol.

I'd put 1 IS before everything in 2nd because it's THAT good.
But insane 3rd job build is insane...
Personally I'd do this:
20 Burst Fire
20 Cooling Effect
20 Flamethrower
20 Lucky Dice
30 Octo
21 Gavi
20 Homing

Because:
BF and CE first for obvious reasons. Now, Because newt sniping is no longer possible, you need mob skills to train with. What mob skills outlaws got? The new and improved CE+FT combo! I'd max that ASAP to train effectively on roids and gobys. (monsters around the level of maxing the two). after that, lucky dice for random damage boosts because you can and you have nothing better, octo and gavi can be switched depending on training spot, and homing 1 and homing 20 are the SAME...

DoT stacks but grenade still has that silly charge up which makes it annoying.
If you wanna poison train a map though, go for it. Otherwise, ice + fire combo is still better.