take Dinah's Canary Cry away for ten~fifteen years when she gets tortured
"Grell has since claimed that [Dinah losing her powers] that wasn’t his intention, that as far as he was concerned, no one in his series had superpowers, so she never had it to begin with."
Which is stupid, but I think Grell was telling the truth. In his run he kept Green Arrow away from most of the DCU; the only characters he crossed over with were the more realistic superheroes like the Question and Batman (and I think that only happened once), and whenever Hal appeared he was always in his civilian clothes and never his Green Lantern outfit.