i dont understand why it was removed
It was terrible. Any possible scenario where it was a remotely good item there were better choices.
A 1.5 second duration on the healing debuff was the worst offender, pretty much obliterating the chance the debuff would be useful vs. 90% of the healing effects in-game. More than 550 range from Soraka? Useless. Just traded and you backed off? Useless. Healing potions? Useless. Life steal - useful, but you're better off countering that with armor or more life steal.
And Ignite exists for countering 90% of the healing effects in-game, it's there from level 1, you don't have to itemize crit, spend 1800 gold unlocking it, and 50% healing reduction is redundant with it.
Which lead to it Ex Calling having the lowest purchase rate of any item in the game.
And by lowest,
's augment: death was purchased more frequently.
One of Viktor's 4 Viktor-only items was purchased more frequently than Ex Calling. So was Rengar's Bonetooth necklace for that matter.
Having choice and variety is good, but Ex Calling was essentially always a false choice, adding unnecessary burden of knowledge to the game, an extra item to sort through that slows down the search for something useful, and clutter to the shop.
After 2 seasons of being like that: Riot just went with the less is more philosophy. They've removed better items before.