I was recently concepting a champion with the following passive, but I hardly got something cool: "Cannot use basic attacks. Instead, ..."
I am curious to see some original ideas, regardless of the champion role/aspect. Mine is: "Cannot use basic attacks. Instead, deals x% AD + y% AP per second to all nearby enemy champions -- support champion". [slayer-pantheon-popcorn]
Passive: ... Instead, applies one mark of "Targeted" to the enemy it would hit, for X seconds (no caps - duration increased on champions).
Q: Releases a swarm of projectiles that hit all targets for every mark of "Targeted" (consumes mark)
But we already have a champ who don't have basic attack 
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He stores power for skills to be used the more time passes, one of which with a really small CD in order to farm xD
I was actually concepting a champion which couldn't autoattack but instead drained %MAX HP( as true damage?) from all nearby enemies. I was thinking something along the lines of a tank. Abilities would include a dash with stun, AoE slow, skillshot AP dmg, ultimate could be a tether between the champion and an enemy applying passive dmg while tethered then a long root. I scrapped it and didn't do much work but there you go.
Creates a tether between the champion and the target. Other abilities apply different effects to the current tethered target. Different effects depending on if it's an ally or enemy. [Insert 2 sided q, w, e] [Insert some ultimate. Swap locations with the tethered target? Copy the tethered target?]
I'd say, instead of a normal auto-attack, he launced skillshots in a chosen direction instead. Would make it so that you'd still be able to right-click, but you'd have to aim it better. Alternatively, you could also have a sort of Void Ray/Warp Ray from Starcraft 2 beam that just kept on charging on an enemy, dealing more and more damage over time. Attack speed would then scale how quickly your damage increased.
