You know what would be a good idea for a next champ?
AP carry bot lane. All the perks of an adc except ap. I'm always frustrated why the all the other roles need to adjust according to the team but adc always gets away with being an adc. I hate an all ad comp just like anyone else but there's a lot more possibilities if they explore and apc on bot lane. Not in the vein of Morde but in the vein of traditional ad carries. Corki comes close but the way his damage is divided into two kinda still means you need an ap on your team.
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Other than that, there's an overabundance of ad champ in the top lane and overabundance of ap champs in the mid lane. AD mids is basically compromised of ad assassins and nothing else while AP tops is mostly just ap tanks. Where's the ad Viktor? Where's the ap Riven? I think Riot should explore more options and add more diversity in lanes. The meta needs to shift on Season 7 anyway so just make it more exciting.
midlane you have varus and jayce i guess
but i never understood why people want like an ap adc or an ad mage, what's special about that?
what's interesting of each stat is that it makes champions behave very different, ad means you always have dmg off cooldown with ur basic attacks, ap means you'll have pauses between sudden moments of power, etc.
some champions walk the line and that's where things get more interesting. you have azir that behaves kind of like an adc but also has all the benefits of being a mage, or you have ezreal who plays a lot like a mage but is still required to auto a lot to be relevant
if you asked me i would want to see more weird stuff like mordekaiser be an option to adcs, not the same with a different dmg type. would have to be more systems driven than just like a unique case like morde, something that feels less than cheating the system and more like it's something you opt into
so basically an item or two