For the game itself, probably you can combine tutorial with game play. For example in the first boss, you can have the ALL ATTACK option to be highlighted and then you can add on the next turn that if your wizards are damaged, you can use heal (highlight ALL HEAL this time) and so on. I was taught during my previous game jams that only few reads text tutorials and I am one of them hahahaha. Probably for the Tutorial text that you have, you might need proper word choices/small visuals to aid the player.
"Leave one wizard behind to guard you advance after each fight"
What is this advance or wizard? Is this the team itself, the level, the beast? If a small visual is added like for example the three beasts that you have then I can say, "Ohhh so it is my team to be protected". I hope this makes sense :D
Oh and another thing, would be cooler if there is an idle animation for each beasts :P