Urgot ult + gunblade

Only works on dummies since they can't die, Urgot ulti does 100% current health damage as tru damage and then adds true damage until you die (10-1'000'000)

This is totally a legitimate post depicting a real in-game scenario in which Urgot builds Gunblade, 3 Warmogs, Stoneplate and Cinderhulk and ults dummies who can't die by any means.

All I can say is this is how the gunblade healing works with it:

Only the current health damage will count as Urgot's damage and apply Hextech Gunblade item.png Hextech Gunblade's healing.

That would only work on someone with 10K HP. Because it deals true damage based on HP then it wouldn't heal that much for low HP champs.