The new Cassiopeia concept fits Veigar more than her.
Veigar is a single target burst mage who transfers into a DPS mage once he gathered enough stacks for his Q to deal meaningful damage (and build Lichbane).
Cassiopeia is (was) an AoE DoT mage with a SINGLE single-target-DPS ability, which also required another ability to set it up.
Veigar had a powercurve which left him with a bad earlygame, yet an insane lategame.
Cassiopeia had a very balanced powercurve. Her viability didn't change much from 1 to 18. While other mages spiked at certain points (E.g. Syndra with ult and maxed Q), her power remained constant.
- Her damage was very dependant on her and her opponents skill to dodge and land abilities.
Veigar lost a lot of power with the rise of AD casters which significantly decrease the impact of his ultimate.
Cassiopeia also suffered from the rise ob high mobility / range champions, yet didn't require much change to be viable. In fact simply undoing the Patch v1.0.0.134 nerfs to her would most likely have made her viable again. Note: That these nerfs were applied due to WotA, Revolver and Haunting Guise used to stack and amplify each other to hilarious levels at that point of time. A synergy which does not exist anymore, thus rendering the nerfs which resulted out of it inappropriate
In my eyes the rework should be reverted. Riot should go back to the PBE with their Cassiopeia and continue experimenting there.
As for Stashu, I think he's the right one to rework / rebalance Veigar. But I hope that somebody else will take a look at Cassiopeia.
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