I feel like an idiot by asking about the same thing again and again, but I'm stuck (again...).
I've made a tower mob farm in a creative world (I've learned my lesson; creative first, survival second) to work with my Blood Altar. The suckers fall, Dagger of Sacrifice, happy face...
Except... No happy face. They fall alive with half a heart. It appears that the dagger does not work with half a heart. I know because the bats that came down sometimes were hit (3 hearts, full HP) and died at once giving the 500 LP they should. I tried moving the altar up a bit and found that the mobs only spawn 24 blocks away from you. I though "let's ease the fall" with a cascade of water, but they just drown a quarter of the way down. There are no slime block slabs I can use and I'm out of ideas.
Anyone got any?
Edit: I actually thought up something that works. Instead of directing the mobs to the centre, I used conveyor belts and lowered them 2 blocks before sending them to the center pillar. They drop with two hearts and it works.
New problem: Creepers. I hated the bastards, now I loathe them. Even with half a slab as a window so I can just stab the mobs, they drop, see and blow up...
So the first problem I got handled. But if you have a more elagant solution, do share.
As for my second problem... What do?