How to earn almost 1.4 mln XP per hour - an extensive guide to XP farming in HotS [OC]

What is XP farming or "AI farm 1h"?

XP farming in HotS is done by 5-man premade teams playing games vs beginner AI while using a variety of techniques to maximize XP gain. One such game takes about 55-65 minutes on average, hence the commonly used name.

Why would I do this?

Because it's the most time efficient method to earn XP in HotS. Screenshot. Over an hour long match players earn:

Bonuses	XP
Raw XP (no bonuses) - maximum possible per match	500,000
5-man premade + friend bonus	875,000
5-man premade + friend bonus + stimpack	1,375,000
5-man premade + friend bonus + stimpack + 1st win of the day	1,625,000

Now for why would you want that much XP, there are many possibilities:

You like yellow borders around your heroes in draft and showing off with sophisticated mastery taunts
It's event time and you want to earn as many those sweet event lootboxes as possible
You want to quickly level your 1 heroes to level 5 to be able to pick them in HL and get these 4 easy lootboxes + 500 gold. Incidentally, 1,375,000 XP earned by a level 1 hero is just enough to get them to level 5.
Or maybe you come from MMORPG roots and just enjoy grinding ;-)

Don't you get bored playing vs beginner AI for 1 hour?

Well, that depends. How good are you at finding things to do? Sure, if you were to focus 100% of your attention on prolonging a beginner bots game, it'd probably get pretty boring. Many people however find other ways to occupy themselves.

Some of them soak/hunt with heroes with infinitely stacking quests, such as Alarak, Butcher or Arthas's D and become absolute raid bosses during that 1 hour. Some people watch TV series on second monitor. Some others listen to podcasts/audiobooks. Some others engage in some of the legitimately funniest/most stress free banter I've had pleasure to participate in HotS. (Usually during regular matches you don't have much time to type/joke, unlike here)

Isn't that an abuse of the XP system? Won't I get banned for this?

No. Farming XP in AI games is not forbidden by Blizzard ToS. Source.

How do I find people to XP farm with?

Join the in-game channel xpfarm by typing in chat /join xpfarm <enter> . Advertising on reddit or lfg channels is also a possibility. However, when using the latter, take care to note that it's xp farm 1h, so people looking for AI rush games don't get mistaken. (AI rush - grinding multiple AI games as fast as possible to earn gold/quests, quite the opposite of what we're trying to achieve here)

XP Farming 101

Quickstart: Alright, I'm sold, how do I do this?

A quickstart guide, step by step:

Type in chat /join xpfarm and say there something inviting, like "looking for xp farm 1h"
After finding a party, remember to friend one of them for the 25% XP bonus.
After you have a 5-man party, queue for Co-op vs. AI (Beginner) mode.
If an unacceptable map has been chosen, wait until the game loads then leave immediately. All party members need to do this.
Repeat above until you've started a game on a favorable map (preferably tier B or higher from the table below)
Assign roles - 3 players should be soakers and 2 should be feeders.
If you're a feeder:

Keep dying to enemy towers/core/heroes/minions as frequently as possible (you can destroy a wall to get deeper into the enemy base so you can get focused by more towers at once)
If your team's keeps are already gone (usually at 20+ mins), you may need to help the soakers defend the occasional AI 5-man core push
Your feeding gig is done when enemy team hits level 30. There is no point in feeding after this point, enemy kills are now worth as much XP as possible. Now you become a hunter - your job is to kill enemy heroes until the 500k exp goal is reached.

If you're a soaker:

Go to a lane and soak as much xp as possible.
Keep in mind that your goal is prolonging the game to last 1 hour; that means that early game you shouldn't push or even damage minions at all. Xul is terrible as a soaker for that reason, since he can't control his trait.
If you are playing a hero with decent waveclear, you can give up keep in your lane - it will allow you for more freedom in clearing waves due to catapults.
After giving up a keep feel free to take enemy fort + keep wall in that lane. That will also allow you to camp and hunt enemy heroes closer to their spawn. Be careful not to overdo it though; don't take keeps.
Feel free to kill enemy heroes if an opportunity arises, don't forget your priorities though: 1. Defending endangered core 2. Soaking lane XP 3. Going for enemy kills

After both teams hit the maximum level 30 (this usually happens after 45 minute mark), it's still not over - you are going for the maximum XP gain, which is 500,000. You can check the current XP amount by hovering your mouse over the level number at the top bar.
When the XP counter reaches 485,000, it's safe to start going for enemy keeps. The XP from taking down the structures + a few waves + a kill or two should be enough to get you the remaining 15,000.

Again, 500,000 XP is the cap, so any amount earned over it will be just lost.
Be careful, if you go too much over 500,000 XP, it overflows, "zeroes out" and you get 0 XP. As the most I've personally earned is about 510,000 XP I can only say it for sure it doesn't happen then. Verified information on this matter, preferably with video evidence, would be welcome here. EDIT: I've received reports from people in comments below that the overflow happened to them at 520,000 XP. Go above these amounts at your own risk!

Enjoy your XP! If you have done everything correctly and have a stimpack, you should have earned 1,375,000 XP in about 60 minutes!

Battlegrounds - what maps are suitable for XP farming?

Not all maps are suitable for farming XP, as shown in the table below. Depending on how picky you are, you have about 40-50% to get a good map every time you queue for a game. A very often used trick to reroll maps is to leave the game just after it starts, as there is no penalty for abandoning AI games, especially if all 5 members of a premade party do it.

Battleground	Tier	Comments
Warhead Junction	A+	Very good map. Soakers can keep some nukes in reserve to help with waveclear/emergencies. There is also a reported possibility to farm bosses for locust XP. (no longer possible as of 2018-04-24 patch)
Cursed Hollow	A	A classic. Giving up objectives is very safe, as long as the soakers don't lack waveclear.
Dragon Shire	A	Approaches vary - some players here prefer to cap the objectives and soak midlane as a badass dragon, some others prefer to cap one shrine and abuse AI tendencies for going for the other one, or infinitely juggle both. Either way it's a very good map with low risk and a lot of room for error.
Hanamura	A	As reported by /u/phoe-nixx in this thread, I haven't verified it myself.
Towers of Doom	A	A unique possibility of infinitely recapturing/giving up structures for more XP. Room for error is also quite big, all you have to take care about is to not capture all 6 forts by accident. Best played with a hero good at safely stalling the bottom altar.
Volskaya Foundry	A	After recent patches beginner AI doesn't even put anyone into the Protector after winning objective, making it safe to give up. Safe to take camps giving lots of XP.
Tomb of the Spider Queen	B+	Similar to Blackheart's Bay, but even easier due to small map size and allied deaths not dropping tons of coins, giving teams more room for error.
Blackheart's Bay	B	Late game (after giving up keeps) good map control is needed to make sure no enemies with coins can survive, slip through and pay.
Garden of Terror	C-	Objective pulls heroes away from lanes and soaking for a long time, coordinated effort of whole team is required late game to kill enemy lategame terrors / not allow them to gather enough seeds. Annoying, can drag on for long and not a lot of room for error, but doable with a good team.
Infernal Shrines	E	The objective late game is very dangerous. Stalling it is theoretically possible with very good single target damage heroes, but it's definitely not worth it unless you're desperate or bored.
Sky Temple	E-	The objective in theory could be stalled by a very coordinated team, but it's definitely not worth it.
Battlefield of Eternity	F	2 lane map
Braxis Holdout	F	2 lane map
Hanamura	F	2 lane map
Haunted Mines	F	2 lane map

Most groups I've met reroll the map until getting a B tier or higher, although there are some pickier players who only go for A and higher. I've also met with some wanting to reroll Towers of Doom, probably due to not understanding the potential of this map or not having a good hero for stalling the bottom altar.

Advanced tips

For the feeder role, heroes and talents letting you get under enemy forts/keeps faster are preferred. Some good examples: Leoric, globals (including e.g. lev 20 Auriel and Hanzo), Cho'Gall (shorter respawn timer at 20)
One more note for feeders - only dying to enemy units (heroes, summons, structures, minions, captured mercs, ToD killzone) gives XP to the other team, so don't get creative on cursed hollow or towers of doom and try dying to neutral boss camp because it's closer to base - it doesn't work :)
For the soaker role, heroes and talents giving you waveclear, sustain and kill potential are best. Infinitely stacking quests are also nice to have, e.g. Zul'jin, Butcher, Arthas. Some soakers might even help your team feed more efficiently, e.g. Misha, D'Va, The Lost Vikings (TLV let you have more than 2 players as feeders).
If your character is good at taking merc camps, you can do it in-between soaking waves for some extra XP. This is especially worth it on Volskaya, where merc camps are worth a lot of XP and don't push uncontrollably, risking taking enemy keep. However, after the keep in your lane falls, you can let 3-4 enemy catapults stack without killing them and then cap a pushing merc camp - even the knights camp will quickly die to 4 catapults bombarding them.
On Towers of Doom, it's usually best to wait until the bottom altar spawns - that way the person stacking bottom lane will be able to both soak and interrupt enemy channels. A soaker who can interrupt channels safely is best for that role, e.g. Chromie, Azmodan, Nova (clone).
On Towers of Doom, every time a fort is captured/recaptured, it grants a big chunk of XP. Take advantage of this to achieve 500k in record times! (Although take care not to capture 6 bell towers at once, it's usually game over if you do that)
The AI has many patterns you can learn to recognize and abuse. However, it changes between patches. Recently, they've been taking bosses noticably more often and 5-man core rushing without minion waves a lot - be ready to defend if that happens.
After you've given up all keeps, it is advantageous for soakers to take down enemy forts and keep walls and keep the waves pushed right about to where the enemy forts used to be. Although this makes feeders take a bit longer to get to a place where they can die, it also lets you control the enemy heroes movement more, which is advantageous especially on maps with riskier lategame objectives like Blackheart's Bay. Being closer to their spawn means also catching their core rushes earlier and farming kills more efficiently.
If you're doing something requiring mouse activity on the second monitor during the game, you can set the game to Windowed or Windowed (Fullscreen) mode in graphic options for more convenient switching. If watching TV series / a movie you can mute HotS sounds either in Windows Mixer or sound options in HotS. However, when playing with HotS sound muted pay some extra attention so you don't miss a core rush defense call!
If you like chatting on the ingame channels, e.g. reddit or xpfarm, you can do it also during the game. To do that, enable Show Blizzard channels in-game and Show non-Blizzard channels in-game in Social options.
Why are feeders needed, wouldn't 3 soakers + 2 hunters be enough from the start?
In short, that's because of how XP gain for kills and comeback mechanisms work in HotS. You get more XP per kill if the enemy outlevels you, "regular" amount if you are of equal levels, and next to nothing if you are outleveling them by a lot. Therefore feeding the enemy until they get level 30 is necessary to get maximum exp for kills possible in the lategame. However, feeding after that point is pointless - that's why feeders switch then their roles to hunters.
Why give up keeps? Isn't it enough to give AI the XP from feeder deaths, do you also have to give them structure XP?
I answered this in a comment below.