The game is very buggy. There were several times I tried to connect two squares that were several tiles apart, but when I dragged my mouse across the board, the line disappeared half-way or so (did I move the mouse too quickly?), or the game suddenly shifted to the tile-removal phase and prevented me from finishing the line. Once, the unfinished line even stayed up when the game went back to the line-connecting phase, and I wasn't able to select that tile again. The game even soft-locked on me: while fighting the 3rd mandatory battle (the purple snake/dragon thing), I connected two tiles as soon as my timer ran out, and the game stayed stuck on the enemy's turn with the board removed; I had to refresh the page and lose my progress.
My suggestion: instead of having the tile-removal phase happen randomly during the player's turn, give the player the option to do it manually (maybe even show a preview of the connections' damage/healing during the line-connecting phase). Also, have it happen automatically when the time runs out so the player knows those final connections actually do something.
P.S. There also doesn't seem to be much to explore, but maybe I just didn't make it far enough.