Thanks for the feedback, and thanks for playing! Unfortunately we didn't have as much time as we would like for balancing. One of the challenges with balancing a game like this as a developer was that I was naturally more familiar with it, so its easy to overestimate the ease of someone who hasn't played yet. The game takes a few attempts to start figuring out some strategies and also memorizing a few of the shapes. Remember that the game time pauses when you open the help books so feel free to click through and use that time to plan out your spells ahead of time.
For some general tips, one of the biggest challenges with stacking multipliers is that they burn through much more ink. Casting the rain storm spell every so often is a great way to keep your ink regeneration rate higher. Keeping the uptime on that buff up as much as possible is especially key for beating the final boss, since he attacks much more frequently. It is also a strategy to drag out the fights and play more defensively, especially with the later levels. Keeping rainstorm up, and casting healing potion in response to attacks is a great way to stay alive for a long time. The rainstorm should let you heal from most attacks and squeeze in a few offensive spells to whittle down the enemy health.