There are two methods to boosting this. Both will be explained and separated by a line.
This is ideal for 6-8 players.
The Highest Faction Level is 30.
Achievements:
Killing Joke (Level 30 with Joker Faction)
Fallen Knight (Level 30 with Bane Faction)
Gotham All-Star ( Reach Overall Level 30)
Legend ( Prestige once Overall Level is 30)
Choose whatever map you would like to play on as it doesnt matter. However, i prefer Joker's Funhouse as it is small.
Since there are 6-8 players there will be two players on the Hero Team which is why its better as you dont have to kill the Hero's which will increase the spawn time. Anyway here is the method:
The Joker team will go to the Sun Capture Point.
The Bane team will go to the City Capture Point.
The Hero team will take one Location each. Batman = Sun, Robin = City.
The Joker and Bane team will stay in their Capture Points. The Heroes will scramble the Capture Point by placing a scrambler on the Capture Point.
The Joker and Bane team will destroy the scrambler and get points for it and then capture the Capture Point again.
Repeat over and over again.
NOTE: Bane team has a Tactical Dart which will get you 300xp for tagging the Hero. Its recharge time is 10-15 seconds so make use of the Tactical dart. It will get you to the 15,000-20,000xp mark.
NOTE 2: There are 5 levels to the Tactical Dart.
Tactical Dart v1 takes 10 seconds to cooldown and gives 300xp.
Tactical Dart v3 takes 17 seconds to cooldown and shoots two darts but still gives 300xp.
You will get 1500-1800xp per minute with Tactical Dart v1.
You will get 900-1200xp per minute with Tactical Dart v3.
Bane team without Tactical Dart = 5k-10k exp per player
Bane team with Tactical Dart = 15-20k exp per player
Joker Team averages = 2-15k exp.
Heroes average = 5-10k exp.
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It can also be done with 6-8 players like above or 3-8 players down below.
With this method there is a chance that only one person will be on the Hero team. If this happens then follow the following steps:
Joker Team goes to Sunb Location
Bane team goes to Sun location but camps outside.
The Hero goes to the sun location.
The Joker team will get the Sun capture point. The Hero will scramble it and then th Joker Team will destroy the scrambler. Just like before.
However, Bane team will keep shooting Tactical Darts from outside the Sun capture point. They will hit the Hero and both the Joker team. This will allow you to get 300xp from the Hero plus 200xp from each Joker player. So, 300=200=200=700xp a Tactical Dart shot if with 5 players, 1200xp with 8 players
3-5 players:
Bane Team will hit 40k xp
Joker team can hit 7-10k xp
Hero team can hit 12k+xp
6-8 players:
Bane Team will hit 80-100k xp
Joker team can hit 5-10k xp
Hero team can hit 8-12k+xp
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The Aud Doc comments:
There are Cobblepot satchels that can be bought that sometimes offer an xp boost. The Cobblepot Satchels give random consumables ( Xp boosts), gear, weapon skins etc. Those xp boosts can speed up xp earned quite a bit.