Many other games have a system where, as you earn more training points, you can assign them to your abilities and make them more effective. I think this or something similar would be interesting for Wizard101.
So, adding training points would mean improving the stats of certain spells as you add training points. For example, if you have trained Amplify (15% hit boost), you should be able to assign another point to it and make it Level 2 Amplify (20% hit boost).
I don't think it would be fair to allow players to upgrade spells that only their school can use (e.g., Storm Lord, Tempest, Frost Giant, Frostbite, Forest Lord, Rebirth, etc.), so I'm not suggesting that. However, here are some other examples of upgradable spells that anyone could use:
Level 1 Conviction (+90 critical block, 90% stun block); trained from Diego Level 2 Conviction (+95 critical block, 95% stun block) Level 3 Conviction (lasts 5 rounds instead of 4)
Level 1 Infection (-50% healing boost); trained from Death Tree Level 2 Infection (-60% healing boost) Level 3 Infection (two -60% healing boosts for 1 pip)
Level 1 Reshuffle (4 pips, reshuffles all cards 1x) Level 2 Reshuffle (3 pips, reshuffles all cards 1x) Level 3 Reshuffle (3 pips, can be used 2x before disappearing)
Interesting, but there would also need to be a level set to the upgrades. Though, I think this would be untimely in the current situation of PvP as it's already somewhat of a mess as it is. In the future though, when everything is more balanced out should be fun to see this come into play. -Wolf Deathstalker, Exalted