Goblin Goldfield Mechanics
The point of Goblin Goldfield is to kill as many goblins as you can within 2 minutes. Each goblin has 5 HP has all damage reduced to 1s will instantly respawn somewhere on the map when they die and will not attack you. Every goblin you kill increases the amount of gold you receive at the end of the event and the amount per kill increases as you level up. The amount gold per kill can be further increased by the guild tech called "Plunder Tech". While other events can be won with brute strength alone goblin goldfield requires you to know how character's skills work to be successful. Skills that should be focused on are AoEs multi-hit skills anything that hits quickly and anything that applies burning or poison.

Tips and Tricks

• Zoom out of the minimap so you can see where all of the goblins are
• Avatar skills go into their base cooldown when you enter into the Goblin Goldfield map
• Wait until storm blade is off cooldown before entering; as soon as you click the enter button keep spamming the R key until you load in and you'll be able to use storm blade from the start
• Storm blade will enter its base cooldown of 40 seconds afterwards so use a skill pot to reset it
• Use skill pots whenever you can (unless storm blade's cooldown is under 10 seconds -- use your own judgement at that point)
• Save storm blade for when you can hit 4+ goblins
• Focus mainly on large mobs of goblins going after small groups only if they're between you and the large mobs
• Goblins tend to respawn on the other side of the map
• If your hotkeys suddenly stop working manually click one of your skills to fix this

Avatar Skill and Pet
All 3 classes should be bringing the same avatar skill and pet (if available):

Avatar Skill - Storm Blade: This is the avatar skill to use while running Goblin Goldfield. Unlocked by acquiring the Katrina avatar this avatar skill has no casting animation has a low base cooldown of 40 seconds has very good range (slightly less than mage's w-lightning skill) hits 7 times (again goblins only have 5 HP) and is accessible early on in the game. This skill should be spammed whenever available as well as skill pots.

Pet - Slingfox: While only available to those who recharge for the first time Slingfox's pet skill is very useful for Goblin Goldfield. While it only hits a single target the goblin that gets hit by the skill is guaranteed to die since the poison status lasts long enough to do at least 4 hits. Very useful if you're running to the next cluster of goblins and Slingfox decides to shoot that 1 goblin that's off to the side. Also if you see that a goblin has been poisoned don't bother chasing after it. The alternative is Kitwr--Master Kit if that's your only other pet except it only hits up to 2 goblins with its pet skill. Otherwise any pet that can inflict burn should take priority. Medusa can also be used in place of Slingfox if you have her.

Class Skills to Bring
Mage: (Difficulty: Medium)
Q - lightning: Hits up to 4 enemies and can stun. Q-fire's ability to burn and to hit twice doesn't justify the fact that it hits only 1 target and has a long casting animation while q-ice only slows and the splash requires the goblins to be close together. 

W - lightning or ice: All 3 elements could technically be used but only w-lightning gives the most consistent results and is the least situational. Stick to w-lightning if you can get storm blade's cooldown down to 5 seconds or lower since storm blade hits faster does more hits and has a wider range than w-ice and fire.

• W-lightning fires a large AoE centred around your character as soon as you use the skill. It has the shortest cooldown of the 3 elemental w-skills and has a chance to stun. Another perk of this skill is that it can be used while your character is running without stopping/slowing down your character allowing you to simultaneously chase and damage goblins. The only drawback is that it does 1 hit.
• W-ice creates a small AoE around the selected target that lasts for about 2 seconds and will hit the area 4 times damaging anything within the AoE approximately every 0.5 seconds. Goblins will only take damage if they're within the skill's AoE at the start of each 0.5 second interval. You'll want to use it on mobs that are relatively close together and aim for the centre goblin but selecting the "correct" goblin while they're all moving is easier said than done. The skill does inflict slow but goblins generally won't live long enough for you to take advantage of their slowed movements.

E - fire: E-fire and ice are similar skills; they are both small AoEs (same range) centred around the character. The only noticeable differences are that e-fire interrupts (makes the goblins bounce preventing them from moving momentarily) and burns while e-ice only slows. The burn status essentially makes e-fire do 2~3 damage instead of just 1 and while it doesn't inflict slow like e-ice e-fire will have interrupted them done 2~3 damage and the surviving goblins will still be close enough to follow up with whatever isn't on cooldown (being within range of e-fire/ice means that the goblins are well within range of every other possible attack/skill a mage could use).

Warrior: (Difficulty: Hard)
I hope you're ready to make your character run in circles.
Q - ice or lightning: It's a situation where you're not selecting the best skill for the task but the skill that doesn't make your task a living hell. Q-fire can be ignored because it's only good for 1 thing: hitting 4 times. It doesn't inflict burn like other fire skills requires you to be next to the target to use the skill and despite its ability to hit multiple enemies and flashy skill effects q-fire can be considered a single target move since hitting multiple enemies with this skill requires them to practically be on top of each other -- something that the AIs are programmed to avoid.

• Q-ice despite being a normally 1v1 skill does have a small AoE at the end that can freeze and slow targets that are really close to the initial target. It also homes in on that 1 goblin so it can be used quickly get close to mobs to hit them with your other short-ranged skills.
• Q-lightning is more of a finishing skill; while it can be used to hit goblins that are far away it only does 1 hit so unless that goblin had only 1 HP left prepare to run a mini marathon. The skill could also be used for map control but with only 2 minutes per run that time would be better spent actually killing them instead of setting up to kill them unless you also brought w-lightning.

W - lightning or fire: Another case of "pick the skill that makes me cry less". Fortunately the 2 options are more usable than the 2 for the q-skill -- just not by much. Ignore w-ice since there's no need for invincibility and you generally don't want to use a skill that does delayed damage against runners.

• W-lightning is basically a nerfed version of storm blade; once you use the skill your character will do a total of 5 hits as it spins around for 2 seconds. The radius is half of storm blade's and if you stick to a goblin from the start of the skill it's a guaranteed kill. The drawback is that you can't use any other skills until w-lightning ends.
• W-fire pulls in anything that's close to you damaging interrupting and burning them in the process. Useful for pulling goblins in if they just started running away. The small range on the skill can be annoying but the goblins won't be able to move while they're being pulled towards you and for a brief period after they land.

E - lightning: Warrior's chaining skill that hits up to 4 enemies and can stun. Ignore e-fire and ice since those skills take a while to actually hit and their hitboxes are already weird against stationary targets.

Gori...I mean Priest: (Difficulty: Brain-dead easy)
Ah priest...the only class where you can completely ignore skill cooldown passives and still get a high score in Goblin Goldfield.

Q - lightning: Hits up to 4 enemies and can stun. Q-fire's ability to burn and do splash damage can be ignored since the skill requires you to waste time chasing down the goblins and the splash range of the skill is really small. While q-ice has a longer range than q-fire it still suffers from having a small splash range and only freezes and slows.

W - lightning: This is the event where w-lightning shines. Only w-lightning should be used here since it does damage to anything that's within its decent range. W-fire and ice shouldn't be considered at all since all damage you do is reduced to 1s (making w-fire useless) and the goblins don't attack you (making w-ice useless).

E - lightning: And this (along with w-lightning) is the reason why priests are stupidly broken in Goblin Goldfield. Gorillas move a lot faster than you have low cooldowns (if any) on their skills can last as long as you're on the map act independently of your character you don't have to worry about them getting killed as soon as you summon them and the best part of all: anything they kill counts as your kill. Any gorilla will do even the default one with no elements. However e-lightning is preferred since it has AoEs and chaining skills. The only downside is that the gorilla will teleport to you if you get too far from each other (max distance is about 1/3~1/2 the size of the Goblin Goldfield map) and will then proceed to kill steal all of your goblins until you move to another part of the map (yes that's the only downside).