Might be fun to have some spells, that require you to know 2 (or more) specific spell schools.
Acid Splash
Cantrip, Single TargetDigested KEY.
Requires knowledge of Earth & Necrotic Magic to learn.
Blackflame Dart
Cantrip, Single Target1d12. On crit: Smoldering. Smoldering applied by Blackflame does not end.
Requires knowledge of Fire & Necrotic Magic to learn.
Smoke Cloud
Cantrip, Single TargetCreate a 2x2 opaque cube of smoke within reach. (You can only have 1 Smoke Cloud active at a time).
Requires knowledge of Fire & Wind Magic to learn.
Acid Arrow
Tier 2, Single Targetignoring armor of Digested enemies (removing the condition).
Requires knowledge of Earth & Necrotic Magic to learn.
Mirror Image
Tier 2, SelfCreate 1d4 mirror images. When attacked: You may sacrifice any number of images to reduce a dice face by that amount.
Requires knowledge of Ice & Radiant Magic to learn.
Pyre
Tier 2, Special(Castable only when you kill an enemy) Apply smoldering to another enemy within Reach 1 of that enemy.
Requires knowledge of Fire & Necrotic Magic to learn.
Disintegrate
Tier 6, Single TargetDeal 100 damage on a failed DEX save.
Requires knowledge of Fire & Radiant Magic to learn.