I'm thinking I just don't use GameplayEffect for this at all since without prediction it's useless. Instead I have server & client ticking read a tag that the ability sets, and do their own calculations. I'm not sure if there will be a little fighting over the value during attribute replication because of lag - on the server I guess I could account for that by incorporating the average lag in the start/stop calculation 🤔
Who'd make a multiplayer game eh