I made 3 different designs.

1) This design will detect and extend the piston instantly. The problem with the soul sand is that the mob will fall for 0.3 ( more or less ) seconds when spawns, so the system is too fast, and the mob will fall only with the second shift.

http://ift.tt/1LEkTGK

2) With a repeater the mob will fall at the first shift, but the system is a bit slower than the first.

http://ift.tt/1TwVJAj

3) The mob will fall at the first shift. The system will stop if it happens. If not it will continue as long as the mob will fall.

http://ift.tt/1LEkTWZ

I'm testing the 2 and 3 designs, the first is totally safe. Another problem is that if the witch is on the edge of 2 lines it will not fall cause the timing is different. When the first line is pushed the second is stable etc. They are not farms yet, just ideas I came out with.

Feedback is appreciate.

WARNING: THIS IS A RANT! Ok, so if you launched Minecraft this morning inside the U.S., you saw news of "Minecrate" in your launcher news feed available to those willing to cough up $30.00 (US). Click on the link to the website and find a slick page design to make you drool for what inside the "Box" though you won't know until you pay for and get one… Now I have subscribed to "Lootcrate" before, and its not as great as it lets on, (the best things I ever got was a cool t-shirt, and a Minecraft keychain that broke after the first use… definitely not worth $30.00) so I am not too enthusiastic for this novelty sale. Now, I can't really see paying as much as what the game costs for a box of cheap crap… Beside that point… I am a bit miffed for the embarrassing way that Mojang has decided to "use" the Minecraft "launcher news feed" in the first place. For the past six months to a years, I have not seen one single line about snapshots, release dates, company news other than sales related bulletins or "security updates" (thank-you Microsoft). Hell, there is more posted here on reddit for Minecraft news than in the launcher, and most of it is gleaned off of Dinnerbone and other Mojang employee's tweets! Pathetic… really pathetic.