EPTSome crazy strategy would involve skipping spire to develop hydralurker + queen ensnare midgame bust, earlier than defilers, yet that much faster to execute.
PS: napkin math time; the entire hydralisk tree plus 1 queen with ensnare research costs the same as 7 mutalisks. I think hydralisks and lurkers with a single queen can exert more pressure than 7 mutalisks.
PS 2: 7 mutalisks are equal to less than 5 hydralisks, however against marines they are equal to 9 hydralisks. Delving deeper, that was the attack rate comparison. However defensively, mutalisk still have an edge. Past 10 however, zerg quickly runs out of gas since it takes three times less gas to make 13 hydralisks vs 10 mutalisks, so it would take equal amount of gas for zerg to make +3 mutalisks past the initial 7 that 13 hydralisks would cost. Zerg only has a small units weakness with hydralisks which the queens sort out. With mutalisks as I said, you would need a much slower ramp up past the initial 7 and zerglings to go along with mutalisks. If we were to double army size with mutalisks, you could have 4 times as many hydralisks if you hadn't. Coupled with ensnare, you could run away with the game very easily.
TL;DR: The entire build tree takes 1000/1000 which is the same as 10 Mutalisks and 1/3 of that is the gas cost of 13 Hydralisks, so at 10 Mutalisks & 13 Hydralisks, 13 Mutalisks & 26 Hydralisks, the gas cost is the same.
