As much as Zed turns into a Saturday Cartoon here, there's definitely a reason behind it. The only real question is whether or not Riot are going to go more in depth on the matter. Also can I get a Red to clarify whether or not GP is one of Zed's related champions? Not sure if crazy lore hint or just rito spaghetti.
I don't remember reading anything yet about why Zed seems to be siphoning magic like that, but IIRC in his bio Gangplank was mentioned to have conducted a raid on one of the Order of Shadow's temples.
Its likely that Zeds shadow techniques need to absorb energy in some form in order to function/get stronger.
I mean remember the shadow apprentice who wanted to steal Xayahs soul to get stronger?What if all the shadow techniques work like that? This is further supported by the fact that zed recently got the ability to get stronger by killing strong targets,he absorbs the energy of his victim to get stronger himself. In this video he likely did it to the surrounding nature for more power.
More than likely Riot is hinting at something with Zed's shadow techniques. Thus he needs the natural energy (or magic as the vastayan see it) from runeterra itself to power up. We don't even know how much Zed remains Zed, or how much his ambitions remain his own. Remember there was all thus confusing part of his lore where he let out thus bitch scream, but then he walked out with Kusho's (Shen's dad) head. Zed truly is a man shrouded in shadows.
