yeah, the walkthrough for lvl 12 is far too complicated.
Just take your upper cell, and support the lower cell and the central one, your lower cell supports the central one and attacks his lower cell, and your central cell attacks his two cells. You dont even have to cut a single tentacle.
both for 10 and 17 you should know, cutting a tentacle at the base rushes moge dots to the target than waiting.
in lvl 10 you can rush the small neutral cells, and you have 3 Embryo vs 2 Embryo, while the ant is still neutral.
for lvl 17 you need to support the furthest embryo with the other two, and while it grows the long tentacle, you rush 4 support tentacles before the long one finishes growing.
 "American Racing"){kind=icon}
 "Berserk: The Cataclysm"){kind=icon}
 "Bloons TD 5"){kind=icon}
 "Tentacle Wars"){kind=icon}
 "Tentacle Wars. The Purple Menace"){kind=icon}
 "Rage 3"){kind=icon}
 "Clash of the Dragons"){kind=icon}
 "Wizard's Run"){kind=icon}
 "Shattered Colony: The Survivors"){kind=icon}
 "Nick Toldy and the Legend of Dragon Peninsula"){kind=icon}
 "Fisher-Diver"){kind=icon}
 "Synapsis 2"){kind=icon}
 "Red Remover Player Pack 2"){kind=icon}
 "The I of It"){kind=icon}
 "Dragon Age Legends: Remix 01"){kind=icon}
 "You are a... The Sequel"){kind=icon}