If you are attempting to remove mycelium or grass by flooding it, and you are using optifine, make sure that the 'Clear Water' feature is turned OFF. It's not simply a visual feature, it actually allows more light to go through water which means grass and mycelium will not die underwater.Figured I'd post this here in case anyone else was banging their heads against the wall, wondering "WHY WON'T THIS PURPLE S**T DIE ALREADY?!!?" c:
Instead of making a backup of your map and edit the level.dat, or modify it, you can simply run /gamerule maxEntityCramming 0 in a 1.10, and it'll work in 1.11, without damaging any entities.
Minecraft is 25% off during beta, and it leaves beta tomorrow on Nov. 18. I've been playing since Alpha (maybe a couple months before beta) and I can't believe the game is finally getting released. In a way, it's sad, but it also opens up many new doors.
I am not sure how well known this is, but if you activate subtitles in the audio options of the game, you will be able to find underground mineshafts. When you are walking around on the surface over an underground mineshaft, the subtitles will display the caption, "Minecart rolls". If you dig down and have a look around, voila! Mineshaft.