By using scaling damage. It's not really a scaling, just a way to test if your stat is over a certain number and cast a different spell in this case, but it's better than nothing. Quick proof of concept attached. Principe : -Summon a custom monster -Try to damage him with a test skill -Trigger the improved Buff if it was a hit -Trigger the basic Buff anyway -Make the improved Buff remove the basic Buff That's the theory. But you can see in my proof of concept, I still face several problems : -Impossible to detect a magic hit. You can only detect a kill (my choice, using a custom taxa) or a melee hit (probably smarter). -You're stuck with a summon. Or his corpse. -Combat Text and blood. Since I don't plan to use it, I lack motivation to focus on it... So instead of letting this rot on my computer, I'll share it. Maybe it can help you! =)
