Now that Gangplank isn't supremely overpowered, and pretty much every fighter now beats him in both duel and teamfight potential thanks to conqueror, it isn't too much to ask for access to Death's Daughter for 400 SS instead of 500.
Woodakoodashooda3 votesThat's a 20% cost reduction to upgrade a Global ultimate. If the cost needs reduced to place GP in a healthy state then it should start at a smaller amount, 50 (10%). If that isn't enough then an additional 50 could be cut.
50 per upgrade would still be a huge amount, btw.
Instead of needing 1500 for all three upgrades, you'd need 1350. And if that's still too much for you then it's probably your farm game that is suffering.
The Ecdysiast1 votesIf you break down anything like that, it can sound bigger than it is. "To upgrade" a global ultimate is way too vague for you to claim it's overpowered to ask for a 100silver reduction.