Its great how everything but assassins are basically worthless now

She and many other old late game champions are being pushed to the mid and early game. It's the same story for them as it is for her; if you build tanky enough to survive actual late game damage then you don't have assassination potential, and if you build to have that potential you blow up when caught.

She can carry in the late game, but she is no longer a late game champion. You can thank Riot's push toward late game power for that.

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In what way? she is Item depended and is suppose to be a late game carry

She has always spiked hard with one or two damage items and then fallen off like a rock. It's just how she is designed as a melee champion without any real scalings. Her base damages plus triforce is enough to hurt squishies until the point in the game where they are capable of surviving the initial burst, and then all she does is die if she doesn't build 3 defensive items at least. Additionally the level of peel irelia needs to deal with the later game game goes gets pretty silly.

An irelia needs to snowball in lane or in midgame and end quickly off of that, if she doesn't then she becomes a stunbot just like leesin.