Special Attacks for hard mode enemies

For example:

Skeletons in hard mode have a chance to shoot arrows rapid fire.

Creepers withing a 15~ block radius turn invisible, but they leave visible footprints on the ground.

Zombies are in groups.

Spiders shoot web that give you a slowness debuff.

Endermen have a chance to dodge your attack.

Why do I think this is necessary?
Hard mode, at least for me, doesn't feel hard.
These mobs should have special attacks to make hard mode even more of a challenge.