As a problem that I'm sure I'm not the only who has had.
When you're spell spamming , your chat is flooded with movements and whatnot, so it can obscure the spell/Tier upgrade message. Which can be annoying to realize 30 minutes later, that you unlocked the next Tier a while ago.
So what if we had a sound, as a notification for the player once they've unlocked the next Tier. To alert the player to look at their chat.
So when this appears in chat:
"You have casted 1000 spells in Tier #"
You could receive a noise as simple as the Minecraft exp sound.
This could also work on when you level up a spell as well, as this has the same problem. eg, Novice > Apprentice.
Maybe a different sound for spells than Tiers?
Or perhaps the sound changes each time the spell/Tier upgrades?