Some thoughts on the Hextech Rocket Belt

I'm a mage main. Always have been - I enjoy their playstyles which generally revolve around good positioning and a few clutch escapes/reposition abilities.

I noticed that alongside the addition of the Hextech Rocket Belt, Riot appears to want to nerf Zhonyas, Abyssal Scepter, and Rod of Ages in terms of the AP they grant. To compensate, I assume they intend to add items like the rocket belt with its powerful active. While I admit that if you can pull it off, the active on something like the rocket belt would bring a lot of DPS to teamfights, the nature of what is required to successfully use it in a teamfight is sometimes in direct opposition to what certain mages are good for.

Take Xerath for instance. He is pure poke. He generally tries to stay back during engages to spam his Q/W and peel with his E stun. When on earth would he find an opening to use the dash + aoe fireballs without getting instafocused? The only thing champions like Xerath, Ziggs, Lux or Karthus would do with this item is use it defensively. But would a dash really be enough to negate all-in assassins? Would it be enough to justify the AP nerfs? The Zhonya's cooldown nerfs? I just don't see the mage itemization update as it stands to be an effective answer to tanky AD assassins. And I don't see how it helps the "true" (read : heavy poke, long-range abilities, almost entirely immobile) mages do more damage without being instagibbed.