Normal Mode + Tutorial
So to get started with BA, first grab a games necklace and teleport to barbarian assault.

If you have never done BA before you will need to complete the tutorial. You can do this by talking to Captain cain.


For each section of the tutorial you will have to watch a brief cutscene. This will give you the general overview of BA, but if you're like me and spacebar through everything fear not! I will cover what you learn from this vague tutorial in the guide below.

Normal Mode
After completing the tutorial you will need to find a team to do normal mode. If you have not already, read the rules/getting started page to learn how to join teams in the fc. Once you have 5 people ready to play, head down the ladder and go to the wave 1 room.
Here I will detail the main mechanics of BA and basic strategy. There are more complicated strategies that are necessary to do in hardmode, but this guide will allow you to complete normal mode and learn how BA works.
The Goal of BA is to kill all of the penance monsters that spawn in each wave. There are 10 waves where the monsters will get harder as you progress. There are 4 roles to choose from: Attacker, Collector, Defender and Healer. You must have at least 1 of each role on the team.
These 4 roles correspond roughly with the 4 types of penance demons you find in the arena.




Attackers have to kill the fighters and rangers using a certain stance.



Defenders have to kill the runners by dropping food and leading them to a trap.


Healers have to kill the healers by poisoning them with the correct food and heals other players using holy water found in the arena.


Collectors support the team by collecting eggs dropped from dead monsters and using the cannon to shoot eggs at monsters.


Calling
The Catch with BA is that each role does not have the necessary info to do their job. The Attackers don't know which stance to use, the collectors don't know which egg to get, the healers don't know which poison to use and the defenders don't know which food to drop. What's worse is every 30 seconds, the correct one changes, so you have to adapt.
It's like a game of telephone- the Collector tells the attacker what stance to use, the attacker tells the collector which egg to get. The healer tells the defender which food to drop and the defender tells the healer which poison to use.
You are given a horn that you can use to call for your teammates. You can also use abilities found in the hp tab. These abilities only appear once you have selected your role.


Wave #
Who is telling you what to do
Which action you take
What to tell your teammates to do
Once in the game it will say what to call and do at the top of the screen. The ear icon is what your teammate tells you to do, and the mouth icon is what you must tell your teammate to do. The word next to the ear icon will remain blank until your teammate calls!
Video on how to call


Attacker tells collector what to do, collector tells attacker
what to do. Healer tells defender what to do, defender
tells healer what to do.


Role specifics (What to do)
Gear requirements: For each role try to have at least tier 70+ armour. For the attacker role you should have tier 70+ weapons in order to kill penance.
Below is a map of the barbarian assault arena, labeled with where each monster spawns. The map also shows where each role should go to do their job.

Dispensers
Healing water pool

Attackers run northwest, put on the right stance, and use combat to kill fighters/rangers. This is labeled on the map in red.
Example:
Your job is finished when you see the message:


and
Collectors run northwest with the attackers and collect eggs. Then load them in cannon. This is labeled on map in yellow.
Example:
Help all the other roles finish killing their monsters.
Healers get their items from the dispenser and fill their vial at the pool. Then run Northeast and use poison on healers to kill them. This is labeled on map in green. They will also heal any player who is dying.
Your job is finished when you see this message:

Defenders get their items from the dispenser, and then run northeast dropping correct food to lure runners to trap. Drop some food on the eastern trap, and then drop food near the runner cave. A quick video guide for defending is shown below.
Notice how I call every 30 seconds!
You can see my calls keybound to 123
Your job is finished when you see this message:

The Penance Queen (wave 10)
So you've made it past 9 waves and its time for the final boss? Well here's what you need to know. The final wave 10 consists of a pre-boss phase (which is identical to wave 7) and then the boss phase. The penance queen will spawn after all of the other penance monsters have been killed. (or after 4-5 min from start of wave)
After you finish the pre-wave and the queen spawns, your team will need to craft 8 omega eggs, and fire them at the queen to kill her.
Here is the strategy: (Taken directly from Rs Wiki)

Below you can see what the spiked mushrooms, poison springs and lava crateres look like, as well as what the yellow eggs look like where they might spawn. You can see the cannon interface when firing at the queen, and the gif shows how you can pass an egg to another player.


Yellow egg (can appear anywhere on ground near queen)
Spiked Mushroom
Poison Spring
Lava Crater
Passing an egg to another player
Wave 10 cannon interface. Choose the yellow egg queen option

Once the queen is dead, you will have unlocked hardmode (and comp req is done)! Congrats! You can visit the hardmode guides section of the website to learn about hardmode but please note the strategies are very different than what I have outlined here.