The Hammer...(Forward-B)

[Devilution]

Does anybody use this...? It's REALLY strong...and it has great priority, though I only use it while in the air because on the ground it lags to much. The first hit is more of a vertical trajectory...and the second hit is like a semi-spike. I've killed with this multiple times when the opponent has 80-100%. If used in the air and you land with it...it doesn't have that much lag so it's very unlikely that you'll get punished for it.

 

[Cereal Rabbit]

It wouldn't be the best approach because it is easily punish, but it's excellent for ending combos or edge guard infact. You can even use it for punishing lag, though I would recommend smash attacks.

 

[Shiken]

use it sparingly and youll often score surprise hits with it, especially the second swing.

 

[h1roshi]

a good way to use it, is to come from one direction in the air, and cross over them and aerial hammer them from behind.
to elaborate:

my kirby is falling from the air from my opponents right side. I am flying towards him and i go straight past him, and as soon as i get on theri other side, i'll hammer in theri direction. this is not gauranteed by any means, but it is a safer, more unsuspecting way to use it.

-hiro

 

[Plasmaexe]

The 2nd swing with the aerial hammer is probably the best thing about the hammer since it's got a crazy amount of horizontal knockback. At under 20%, you can even connect the aerial hammer after a forward throw a lot of the time. It takes some time though to learn when to use the hammer to get the 2nd swing on someone, especially a small character.