Mail is a feature in game where users can obtain messages from game characters and developers, usually with rewards attached, or an unlockable feature like Mastery Perks.
Mail works in a similar feature to Codes, however these are highly customisable and can be sent to certain groups of players instead of a widely available code.
You can see your latest mail by clicking the small rectangular ‘Mail’ Button to your left in the UI. It is only viewable in the lobby. When new mail arrives, a notification will show.
Lists of Mail
Welcome to The Hybrid Cafe!
From: Naru
Hey there! I'm Naru, the Barista that works at the counter. Welcome to the Hybrid Cafe!
To start off, you are given two free towers. You will be able to unlock more of them as you play the game. Come to any empty table to create a game of your choice. You can also join other players' tables. In the apocalypse, teamwork is an important aspect! Be sure to respect other players and have fun!
Oh yeah, here's some Gold. You can't buy much with it, but if you save up, you'll be able to buy some Guardians. These are super strong towers that'll provide great support to your defense. You can also use them to buy some Tower Skins.
Reward: 
100
Invitation to the Mastery
From: Aliza
Dear student, I've been observing your actions, and I am really impressed by your achievements. I'm writing this letter to invite you to what may help you in battle. If you are intrigued, keep reading.
Allow me to tell you all about Mastery Perks. These are special cards that boost your defense in a way. It can either be a boost of a tower, or having their prices shaved. Unfortunately these cards do not work in the Master's field. There is an unknown aura that prevents them from working. Other than that, I'm capable of doing anything. However my power comes at a price. You require Mastery Points to use these cards. Without them, I cannot help you, and the cards will do nothing but drain me.
You earn Mastery Points by leveling up. Every 2 levels, you earn one point. If you're level 100 or above, however, you will get one point every level. It is a simple process. If you can't handle that, you can't handle these powers.
For now, I will offer three Mastery Points, for free. Spend your points wisely, as once you spend it, you cannot refund it. I wish you the best of luck, and I am looking forward to what more you can do.
One more thing, I'm not helping you for nothing. One day, you will need to repay me. You do not need to worry about that for now, but I will remind you not to be greedy with your power, as you will end up in shame. You have been warned. Collect the Mastery Points attached to this letter, and you will have access to meet me anytime. Just don't bug me, or I'll kick you out without hesitation.
Reward: 
3
I Need To Tell You Something..
From: Aliza
So you've triumphed all fields on an area. Big Deal.
However, it is indeed an impressive feat. You were able to survive all fields, including the Master field. Don't be so arrogant. You haven't even seen the deadliest field yet. I'll explain.
There's another field that's contaminated with Voids, and this one is a lot harder than you think. The hordes that come with this field overwhelm even me. I like to call this the "Grandmaster" field.
In this field, none of my Mastery Cards work, which already puts me at a huge disadvantage. You're going to discover some new Voids with abnormal powers, and an encounter with the Void Lords is inevitable. If you can survive all that, I'll reward you nicely. Real nicely. Plus, you owe me one anyway.
In addition, Mayla is gone. I do not know where she went. She stopped responding after I mentioned this field. So, entering this field is going to charge you. Magic isn't free, and it takes a load of energy to travel there. 500 Gold for each entry, but I'll treat you for two runs just so you can get a feel for it.
Anyway, I wish you the best of luck. And let me know when Mayla comes back from wherever she went. Goodbye.
Reward: Access to Grandmaster and 1,000
A Special Message
From: Hayaka Nekokami
Dear Player, It's truly impressive that you've managed to defend against the horde of Cold Voids. Defending against the Absolute Zero was definetely not an easy feat, but you've pushed the limits and prevailed.
The Nekokami Clan has been trying to hunt down these zombies for a very long time, yet, when they've emerged, we were not able to defend against them. I, Hayaka Nekokami would like to personally thank you for your contribution. The other clan members have also heard about your victory, and are also very impressed.
As a reward, I have these gems that appear to be valuable to you. I heard these are used as seasoning? Well, it's all we have, everything else doesn't seem suitable as a reward. Either way, again, a million thanks for helping us defend against the Cold Voids. We're looking forward to see what else you're capable of..
Reward: 
2,500 and Void Ice Hayaka skin
Happy New Year!
From: Mayla
HEY! You know what time it is? We're almost into the New Year! And you know what THAT means? I'm about to get my yearly salary! I don't think I've told you this, although it's obvious, I have a job. Still wondering when you'll start applying for jobs..
Anyway, I'm writing to know what you're doing for this New Years. Got a resolution yet? You know I do, and it's going to be the same every year. Money, money, MONEY. I know you want me to pick something different, but believe me when I say that we have no time to WASTE. That Nekokami leader is going to inflate everything to the brim if she ever takes over! Even Hybrid Crops Inc. will crumble if they don't do anything until then. I'm not crazy!
Enough about that. You plan on eating something special? Knowing you, you'd probably buy some budget meal and eat it all alone. I attached some seasoning to the letter so you can add some spice to your Savers Meal. I'd accompany you to give you some REAL food, but I'll be going out with someone else. Alright, that's all from me.
Hope you have a great New Year. Don't be all lonely again this time! New year, new everything! New zombies? Hope not! Anyway, I'll see you later, in a new attire! You'll see what I mean.
Reward: 150 and Neo Mayla skin
10 Million Visits Message
From: Billie
Dear Player, thank you for helping us reach 10 million visits on Arena : Tower Defense. This is a huge milestone that we never thought we will ever reach.
When we first started development, we didn't think we will reach such a height like this. This would not have been possible if it weren't for your overwhelming support, and I am most grateful for all of it. I could never ask for a better community, and I love you all.
I hope you will continue to enjoy our work, and help us reach even higher achievements. We will always work hard to provide the greatest there is for our community.
As a reward, this letter should include some gold and streetcred (provided by Mayla). Again thank you for supporting us,. And here's to another 10 million visits?
Reward: 500 and 1,000
The Black Blizzard Event is on!
From: Naru
Winter has arrived in the Hybrid Cafe! So, we've prepared some special things for the occasion!
First off, we have a special, limited time game mode for everyone! A new colder generation of Void Zombies have arrived, and they are much stronger than what you usually deal with! Survive 60 waves of these deadly hordes and maybe you'll receive a special reward? I recommend pairing up with some pros, because even I can't beat this!
Next up, we have some limited time Profile Cards and Tower Skins. You'll be able to find them in the Special Shop. Make sure to get them all, because after we wrap everything up, you probably won't be able to get them ever again!
That's all for now! Also, take this free profile card. We give these out to people who've visited the Cafe at this festive time! Anyway, have fun, and good luck!
Reward: Frosted 2021 Profile Card
Guess What I Found!!
From: Akari
Hey!! You'll never guess what I just found.. I was in some tech company headquarters and got my hands on this really cool machine. Looked a little bit like a chaingun, but like, more futuristic.
Apparently it's labeled as "Plasma Accelerator", and let me tell you, this thing is just straight COOL. They shoot out a HUGE laser, even brighter than those red laser dots! I normally sell my findings, but I think I'll keep this one. Maybe one day I can show you!
They also have a manual on it, which is how I got it to work, and it mentioned something about the apocalypse and voids and battlefields. I don't know what it's talking about, but I hope I don't have to experience all of that! A cat like me could never possibly handle those!
There's some people knocking on my door, so I'll have to end the letter here. Hope you're all good!
Later!
Reward: 300
Plasma Accelerator Manual
From: CELRIO
‘’ACCELERATOR’’
‘’BUILD, VERSION -177013’’
This manual is designed to teach new members of CELRIO how to use the Plasma Accelerator and touring on how it works. For advanced use, please consult a senior Technician at CELRIO.
Chapter 1: | Enabling the machine.
In order for the Plasma Accelerator to work, at least two of them are required to be functional. After both machines are turned on, they should automatically emit a laser beam between them.
Safety tip: Do not stand between the Accelerators at all times. It is recommended to put them close to each other when not in use to reduce danger space. The beam is engineered not to harm non-sentient lifeforms, but do take care as some builds are prototypes and may cause side effects.
To reroute a machine to another Accelerator, press the Reroute button to iterate between free Accelerators. Do note that a single Accelerator can host to one machine and can only be hosted by a single machine at a time. When rerouting to an accelerator that is already hosted, its last host will turn off by itself.
Chapter 2: | Determining the power.
Accelerators are weapons designed for the Void apocalypse. It is important to know how much power an Accelerator packs to know if it can stand up against high-rank Voids. A powerful machine may perform weaker when routed to a weak machine, and vice versa.
Each machine has three properties:
- Damage, the damage that is dealt every tick.
- Tick Rate, the time elapsed between ticks. The lower, the better.
- Pierce, the maximum amount of targets affected every tick.
As stated, the values vary when routed to different machines. The host machines damage value is added to the routed machines value to determine the damage. The Tick Rate is the average value between both machines. The Pierce value is calculated the same way as the Damage value; both values added together.
Note: Plus-version Accelerators deal exclusive damage to higher-volume targets, making them strong against Larger Voids.
Chapter 3: | Usage in Battlefield.
Before bringing the Accelerators to the battlefield, make sure to only bring non-prototype versions to prevent any accident or malfunction from the Accelerators. It is highly recommended that two troops are responsible with each one Accelerator. No machine should be left unmanned. The beam is designed not to affect those with sentience, so the beam can be shot between other troops.
For positioning, it is most effective to place the accelerators in long, straight paths, to utilize the most of its pierce.
Thank you for your contribution to the battlefield,
Gallery
