|290pxI BELIEVE I CAN FLYYY|
If the roll is successful, falling damage is reduced by 3.5 hearts. If a graceful roll is successful, falling damage is reduced by 7 hearts. Although falls can still be fatal, you will be able to fall an extra 7 or 14 blocks before dying.
When you raise your acrobatics level, you will also slightly increase your dodge chance (it halves all damage taken). It appears in game as *DODGE* meaning it halved whatever damage you were going to take (note: if you are killed by something you cannot dodge ex. you can't dodge if you only have 1/2 heart left). The dodge chance is capped at 20%, when you reach level 800.
The experience gained from falling is tied directly to damage done by the fall. Each half heart of damage earns 120xp from a fall with no roll, or 80xp from a fall where a roll or gracefull roll was executed. Damage before the roll/gracefull roll damage reduction is used to calculate the XP gain. If the fall is fatal, no XP is earned. Because a player has a maximum of 20 health, the maximum XP you can earn in a single fall is 2280 (19 * 120), or 2800 from a gracefull roll fall (19 + 16 * 80). Currently, a fall with Feather Falling armor equipped will net the same XP as if you didn't have the armor on, but without suffering the full damage. Because of this, you will also earn no XP for a fall that would have killed you if you didn't have this armor equipped.
Another key thing to note is that in vanilla Minecraft, you take 2.5 hearts of fall damage whenever you use Ender Pearls to teleport. This fall damage does apply to Acrobatics exp, and the exp gained is calculated with the above formula, equalling (5 * 120) = 600 exp.
Using Ender Pearls 16px is probably the safest and most reliable way of gaining Acrobatics exp. If you have access to The End, not only is farming Endermen great combat exp, and mining End Stone great mining exp, the stacks of Ender Pearl will come in quite handy for Acrobatics. Since the fall damage you take each time you teleport is an exact 5 damage, 12px, it is easy to control, and somewhat difficult to accidentally kill yourself with excessive fall damage. Having a stack on your hotbar at all times, and using it to teleport whenever you're at full health is a good way to get lots of exp.
A fast way to train this skill is if your server supports lifts from a plugin like Craftbook . You can then build a small tower approximately 13 blocks high and build the lift. You then simply have to walk off the edge, then use the lift to go back up. You can also do this with ladders (although it is much slower)you can also do /sethome then do /home then jump then /home. Beware that you will take 4.5 hearts (9 points) of damage from falling from this height. You may want to wait a while before jumping again, or wait until your life regenerates.
This method has been patched in an update to prevent gaining such high acrobatics. The grind tower uses a guaranteed death and a respawn at a bed and to maximise experience. To build one, build a pillar up to the ceiling, placing ladders on one side. Build a small platform on the second-highest allowable space, such that your player is at y=128.6 when standing on it. Put a bed there. Put a hole on the floor to fall through.
Climb down the tower and build a platform under this hole such that a player standing on it is at y=107.6. Interestingly, if you jump immediately after respawning, you will be immune from damage for a few seconds, but will still get XP for the blocked damage.This first fall is designed to take advantage of that by causing 18 points (9 hearts) for a normal fall, but leaving the quick jumper at full health. Leave a hole or ledge towards the next platform, and another towards the ground.
Build a third platform such that a player standing on it is at y=86.6. This will cause 19 points of damage if one does not roll. Note that one should not attempt a graceful roll here. Leave a ledge facing the fourth platform
The fourth platform should be built such that a player standing on it at y=76.6. A regular fall to here will cause 4 hearts of damage. This ledge is in case the jumper rolls on the third, leaving him with 4.5 hearts. Otherwise, this is fatal.
The last platform, hopefully at or near ground level, is at 71.6. A player falling here will take their last half-heart of damage if they do not roll. Because it is possible to survive to this point, have a device that guarantees a death, such as a chunk of burning Netherrack or exposed lava. This should not be directly where jumpers land, else they will not get XP.
For jumpers approaching or above level 500, where a graceful roll is guaranteed if attempted, the best method for training is to jump directly from the second platform to the fifth (107 to 71) and attempt a graceful roll. If successful, they will have only half a heart left, so they can jump directly into the flames to die and restart the jump.
you could build a tower 23 blocks high and use ladders up, if the server you're playing on supports /sethome, you could climb up, set home and just walk of the edge, then use /home command, but you will have to wait for health to regenerate.
Note: DO NOT JUMP, that will kill you. (If you want to also jump make it 22 blocks)
Edit: You can make a 21 block high tower, with a spawn point setted on top, while jumping down on a catus, which has 1 heart left,(exp gain) but also will kill you by the catus, (which spawn you back to the top)
create a tower 23 blocks high to leave you half a heart of health. Next build a 1x3 platform on top and place a bed. then put another ledge below 1 block forward from the bottom of the tower that is deep enough to kill you. now tap forward and fall tap forward and die. This is the simple version if you want to get fancy like me put a stone or wooden pressure plate and a piston at the bottom of the 23 block fall now you only tap forward once. Note: as of mincraft 1.1 I know of no vanilla way to to make it fully automatic. Because if you put a pressure plate at the top of the platform it counts as a block to the bed spawing mechanics. therefore you will spawn on top of the bed and you have to move onto the pressure plate.
Create a tower 22-23 blocks high with ladders on the front. Put a pressure plate at the top that will power a piston to push you left/right. Have it delayed to power another piston that will push you backwards off the tower. At the bottom of where you would land, put another pressure plate connected to 2 dispensers. Again, have it linked to a piston to push you backwards off the plate, then another to push you towards the ladders again. Fill the dispensers with Instant Health II splash potions. Upon climbing the tower, you will be thrown down and you should be fully healed and pushed back to the ladders to climb again. Due to limitations of the dispensers, you can only have 9-10 drops before the dispensers run out of healing potions, leaving you with very little health on the final drop. Holding W to move forward and pressing Alt (Windows) would make the player move forward without the key being held down. But there is still a limited number of drops the player can have.