Please implement some sort of system where you can boost all the character by one level or at least boost all of one class that you have on the field. I like the customization available but in New Game+ and the Challenges it gets really tiring having to boost so many characters in the beginning (can we say carpal tunnel?)
Boost all button
To reduce clicking, I use keyboard a lot - selecting defenders by keys, placing with mouse, boosting by keys…
While a boost all button would be nice to have on battle start in a few later cases, I guess there are many things that are needed more 
. and there isn’t much room in the interface now…
What Coyote said. I use QWERTY and ASDFGH to place defenders, and lots of B button mashing for Boosts. It does make things a lot quicker and more efficient, if you’re willing to put in the time and effort to get yourself accustomed to using some of the Keyboard shortcuts. Said shortcuts also provide a great way to quick-cast Azra’s spells. You can have your mouse in the playing field and still fire off, say, Frenzy with a quick “press 2, left click” rather than dragging your mouse pointer over to the UI on the right.
I couldn’t play without keyboard actually. To me, defenders are not Slak and Ketta, but QA and WA If I want to disable/enable skills, I rarely select the defender by mouse.
I don’t oppose the idea of mass boosting, I just consider it a very low priority. What I’d like to see is the ability to summon defenders already boosted, and an ability to teleport boosted defenders (at the same cost as recall/summon/boost) - simply for practical reasons, to save time and effort.
Technically, it takes no time, if you pause. I also discovered a glitch or Easter Egg that allows you to save lots of time on boosting and summoning and not have to wait for their annoying aura to fade (well, it still fades, but it saves you from having enemies escape in that time.)
Yeah, the game really is designed to be played with keyboard and mouse. Like coyot, I place all of my defenders using the keyboard - the mouse is just a pointer for the map and rarely actually clicks on a button in the user interface.
epicazeroth - it is not a glitch that allows you to boost up currently-summoning units. We wanted to let players place and upgrade all units right away. We actually spent a while arguing over what sort of visual to use for it. Originally you couldn’t see the characters, which is more accurate for a summoning animation but very difficult to identify them for boosting. Glad you found it useful!
@Anthony: You’re referring to how if you summon, then pause, the aura fades and they can attack without delay - like I am - right?
FYI:
The regular summon animation is about 4x as long as a boost animation. So, if you summon a unit and then immediately boost it, that unit does become available quicker. This wasn’t exactly intentional.