How to have multiple attacks that an entity can do?

use a numeric NBT 

which constantly goes upwards

when it reaches certain value

use procedures to make the attack

what evoker does. is similar to this but more improved

it summons several entities. towards his target. these entites have this same value

when it reaches certain value. and an entity is colliding with it. deals damage to that entity

and sometimes summons that annoying winged things

be creative with this

is used on almost Every game with a - path attack like -

You could use

on loaded entity tick procedure

for the top block, and then

if [is [Event/target entity] (sub)type of (CUSTOM:(your entity here))
do Set [Event/target entity] data number NBT tag ["(your nbt here)"] to [Get [Event/target entity] data number NBT tag ["(same nbt here)"] + [1]]
Note this is in BLOCK procedures, not actual JavaScript

yea kinda