Props to Taima Nin for all the blog stuff.

http://www.dmm.co.jp/en/netgame_s/taimanin-asagi/
You need an account on dmm to play. ALERT: Anons have reported that Australia and New Zealand are blocked from DMM.

http://pastebin.com/G5zxPkbV
Guides, Info, FAQs, and other knowledge.

http://taimanin.blogspot.com/2014/07/taimanin-kessen-arena-starter-guide.html
Good starter guide, explains menus and what most things do. (some stuff may be outdated)

http://taimanin.blogspot.com/2014/07/taimanin-asagi-kessen-arena-raid-bosses.html
Explains Bosses, combat, and Atk/Def units. (some stuff may be outdated)

http://taimaninarena.wiki.fc2.com/
Japanese wiki.

Im pretty dead
Current event ending timer

http://pastebin.com/WQj3AnTM
More info on skills

http://pastebin.com/MZfGeqQC
Card name and skills translations. What's my waifus name? (outdated)

http://www8298uj.sakura.ne.jp/asagi/raid_simu.html
Team-Raid boss simulator

https://mega.co.nz/#!wsBBWKYA!rVSzPuNicumYmBnu_fCoKXgZKvdtcFMJKXC-QkrlyXU
http://gelbooru.com/index.php?page=post&s=list&tags=taimanin_asagi_battle_arena
CG collections. (Last update: 05-04-2015)

https://mega.co.nz/#F!Ywx1yArY!Iw0m5Yn45FCyz5wMjqL_IA
Offline scene viewer+guide. Watch h-scenes without playing the game. 

http://spidfan.tumblr.com/
Translated summaries for hscenes and events

Firefox: https://mega.co.nz/#F!qM8wnQTb!r-MjNsBhKLpLXnNhU1oVPQ (English translation for addon options)
http://www1.axfc.net/u/3286221 (original Japanese addon)
Chrome: https://chrome.google.com/webstore/detail/fkoajncfjnckcaibdlbodapepddglnha/
The above addon makes your hscene interface much more like a Visual Novel. You can look at past dialogue, hide the text box, change opacity, as well as a lot more stuff under the addon settings.
Firefox, drag the file into your browser window. Chrome, automatically installs.