Credits: Newbie Guide to Starting Right by Pylamb
Some things to remember before you start your account:
The game is free to download but has pay to win features.
You can only play one account per device, in order to use another one you'll have to unbind your previous details. This comes with a strict warning that might jeopardize your account details.
The current version takes up 67.78 mb, and may exceed 100mb if you don't regularly clear your cache. This might cause performance issues later.
If you plan on being competitive, wait for a new server before investing / spending money on your account. Use the current server as training wheels to get your feel about the game.
As a foreword, it is highly addicting and requires daily log ins to maximize all the game benefits.
New server:
Magic Rush releases new servers per week or more. There were only 2 when this sub was created (last week) and there are now 5 in total.
Accumulate as much diamonds by completing stages and draw your first diamond wishing pool. If you do not like who you get, you may repeat with a new account (unbind then bind a different gmail). Note that this is going to take time to do a do-over, tutorials and all.
The goal is to reach top 1-10 in Arena before the 9pm reset. It takes 2-3 Arena refreshes (16 fights) to get there and 5-6K power (fully level 18-20).
Once you hit top <30, you'll have enough diamonds to do x10. Doable within the day.
Now that you have a solid team, it's now the right time to spend diamonds and purchase with $$ in case you run out.
Staying on top Arena:
Power is not everything. Team set-up, position and hero type can off set power gaps, maximum of 1k.
Try to log in and do arena battles 1 hour before reset to combat sniping.
The first day advantage reaps in diamond rewards and if you keep yourself ahead from everyone else, you won't have to spend much to keep your place. Of course there's a possibility that someone will eventually out-spend you but it will take time before they do and you've already kicked-back from your arena rewards.
You need to spend diamonds. Which means buying stamina, gold and crystal dungeon tries if need be. As long as you keep multiple levels ahead everyone else.
Heroes:
Seeley - Stunner, useful equips and great tank for a free hero.
Lufia - easiest to evolve, extra stun
Aurai - Filler if you don't get a better support, but good for future evolving
Pulan - Awesome tank, ultimate has mass stun/freeze
Chavez - Great as companion with another tank
Crabbie - Massive nuker but takes awhile to regain energy
West - Ultimate can penetrate both mag/phy immune shields
Emily - Ultimate teddy skill distracts and serves as a back-up dmg soaker
Mira - Great marksman for single-take downs
Baggins - Okay as a mage, nothing special
Spartacus / Jacob - alternative if you don't get Pulan or Chavez
Other recommeded heroes are: Murphy and Karna. I'll add more once I get some.
Hero Setup
You'll need at least 1 tank, and 1 healer to clear stages and 3 other nukers. Crabbie is amazing in this area.
For Arena, double tanks work best with heavy nukers behind them. Always upgrade 1 tank first, then 1 nuker, if ever you need to prioritize.
Campaign
Play stages up to your main team's required runes. Farm until advancing to the next color, then play new ones.
When out of gold, diamond or pots, play elite and bonus stages
When farming blue runes, do 10x sweep in cause you need more than 1. It usually dishes out 2-3 scraps and much better than drawing individually.
If you can, only use basic exp elixir. You won't be able to use them past level 30. Stick to your main 5 (important!)
Don't buy from Force Collect until you can buy advance exp elixir (4x).
Don't buy from black/mystery market either since it is a rip off. Always buy elixirs if it only costs gold.
Do at least 1 gem sweep in crystal dungeon. You get extra exp for multiple heroes + equip you can use to reinforce their stats.
Island Crusade
Always use Seeley's Battle Mixture before the end of every battle. It will get replenished each time.
Chavez gets damaged too fast. Reserve him for later stages as fodder tank or until you need him to keep Seeley alive.
Academy
You can stack-up cooldowns by upgrading to the current Kingdom level. So during the time you're online the most, level up Kingdom first, then the rest before you log off of the game.
Upgrade periodically while you're doing something else. So you won't be stuck staring at your phone/tablet or feeling antsy in between waiting time.
Wall
Make sure your team has 2k+ more power than the mine requirement. Once you level more heroes, you wont need all 5 as long as you keep the total power level above what's necessary.
Medicine will be needed to heal your team after every attack. Farm farm farm!
Other players doesn't seem to be interested in declaring wars so keep on mining instead.
Be sure to check watch tower to aid fellow alliance members
Time Management
The game only requires an hour or less to finish most of the tasks. Even less if you mostly sweep.
You can time your game time around arena reset, day reset or stamina bonus times. At least 2x a day (8 hours apart) to use up your accumulating stamina.
Before you sleep / go offline for a long period of time, empty your stamina (by sweeping / playing campaign) and stack up Academy upgrades.