You should give the option to automatically cast the blood spell at a particular level, say, the star limit level for the round, or 10 for the endless.
Evolve to the highest level, build 4 turret spaces and upgrade those to the max, then save up for 1 war machine and two ultimate soldiers. When those get killed, save up again for 1 war machine and two ultimate soldiers, etc. Then you win.
Wow... I still have the high score for arcade mode and I just broke my own record. And I have way more seven tile bonuses than anybody else. Aim for the seven tile bonuses and you'll score high too.