Yes, you are correct about the harpoon; and I stand corrected. As for the boots, saying that having a 50% or so speed boost advantage when you're pure gank isn't beneficial, I'd say you're just talking out of your a**. I ran with Mercury's almost exclusively for a while before finding that swiftness nets me a lot of great opportunities that Treads do not. As for Warmog's, if you read the items section, I don't recommend Warmog's by itself, I purchase it after Thornmail. Next you'll tell me Thorn+Warmog's is useless against a heavy (4+) AD team o.O

The slow on the Electro-Harpoon does stack. Also why would you get boots of swiftness? Boots of swiftness are the ****tiest boots in the game and shouldn't be used on any character...PERIOD. I'm not even going to go into how much of a waste Warmogs is unless you are an AD character that gets Atma's or a Mundo.