I understand that wits end used to be an item that burned mana, but i think that there should be a diffusal blade like item in League of legends, i don't really find it op if it burned 20-24 damage and dealt the true damage amount. Something like a Rylai's scepter or in this case Magina's warglaive.

If you truly understood why Wit's End changed, you'd know why this would never happen.

I actually understand why it changed, but its actually because wits end was op with that price and the mana break, but if you cost it at around 3k or more then it would be balanced

They don't want certain champs like bruisers who have small mana pools to become ineffective during laning/fights taking away any skill.

The Dota demon hunter was pretty notorious at doing this.

As for the purge aspect, gunblade and the bilgewater cutlass both have a slow on them. There is not really that much to purge but that too could be really Op vs certain champions like fiddlesticks who relies on his ult for damage.