Siren and wizard are still the best options. They only pay double at most for any given school. Druid pays triple for war and fire so the cards you need to bank the actions are at a high premium. The wizard is likely still the strongest choice, but i can see a siren with naiya and a boat load of cheap water spells might be able to accomplish the same task

I can see something like this working

[spellbook]

[spellbookheader]

[spellbookname]Siren Blasting Banker![/spellbookname]

[mage]A Siren Spellbook[/mage]

[mage]built by the OCTGN SBB[/mage]

[/spellbookheader]

[spells]

[spellclass]Attack[/spellclass]

[mwcard=PSA03]2 x Tsunami[/mwcard]

[mwcard=MWSTX1CKA01]2 x Surging Wave[/mwcard]

[mwcard=MW1A04]1 x Fireball[/mwcard]

[spellclass]Conjuration[/spellclass]

[mwcard=MW1J04]1 x Battle Forge[/mwcard]

[mwcard=PSJ07]2 x Shallow Sea[/mwcard]

[mwcard=MW1J13]1 x Mana Flower[/mwcard]

[mwcard=MW1J08]1 x Hand of Bim-Shalla[/mwcard]

[spellclass]Creature[/spellclass]

[mwcard=PSC19]1 x Naiya[/mwcard]

[spellclass]Enchantment[/spellclass]

[mwcard=MW1E21]2 x Hawkeye[/mwcard]

[mwcard=MWSTX2FFE07]1 x Rust[/mwcard]

[mwcard=MW1E36]3 x Rhino Hide[/mwcard]

[mwcard=MW1E12]1 x Divine Protection[/mwcard]

[mwcard=MW1E29]3 x Nullify[/mwcard]

[mwcard=MWSTX1CKE04]3 x Enchantment Transfusion[/mwcard]

[mwcard=MW1E31]1 x Poisoned Blood[/mwcard]

[mwcard=MW1E24]1 x Magebane[/mwcard]

[mwcard=MWSTX2FFE02]1 x Akiro's Favor[/mwcard]

[spellclass]Equipment[/spellclass]

[mwcard=PSQ09]1 x Ring of Tides[/mwcard]

[mwcard=MW1Q08]1 x Elemental Wand[/mwcard]

[mwcard=MW1Q19]3 x Mage Wand[/mwcard]

[mwcard=DNQ09]2 x Wand of Healing[/mwcard]

[mwcard=PSQ05]3 x Leviathan Scale Armor[/mwcard]

[mwcard=MW1Q07]1 x Elemental Cloak[/mwcard]

[mwcard=MWA01Q04]1 x Leather Chausses[/mwcard]

[mwcard=MW1Q15]1 x Leather Boots[/mwcard]

[mwcard=DNQ07]2 x Veteran's Belt[/mwcard]

[spellclass]Incantation[/spellclass]

[mwcard=PSI01]6 x Dissolve[/mwcard]

[mwcard=FWI13]3 x Seeking Dispel[/mwcard]

[mwcard=PSI02]6 x Dispel[/mwcard]

[mwcard=MW1I28]2 x Teleport[/mwcard]

[mwcard=FWI12]1 x Minor Heal[/mwcard]

[/spells]

[cost]Total cost: 120 pts[/cost]

[/spellbook]

[spellbook]

[spellbookheader]

[spellbookname]Blasting Banker Air![/spellbookname]

[mage]A Wizard (Air) Spellbook[/mage]

[mage]built by the OCTGN SBB[/mage]

[/spellbookheader]

[spells]

[spellclass]Attack[/spellclass]

[mwcard=MW1A07]3 x Lightning Bolt[/mwcard]

[mwcard=FWA01]2 x Arc Lightning[/mwcard]

[mwcard=MWSTX1CKA01]1 x Surging Wave[/mwcard]

[spellclass]Conjuration[/spellclass]

[mwcard=MW1J04]2 x Battle Forge[/mwcard]

[mwcard=MW1J08]1 x Hand of Bim-Shalla[/mwcard]

[mwcard=MW1J14]1 x Mana Syphon[/mwcard]

[mwcard=MW1J12]1 x Mana Crystal[/mwcard]

[mwcard=MW1J16]1 x Mordok's Obelisk[/mwcard]

[spellclass]Enchantment[/spellclass]

[mwcard=MW1E36]3 x Rhino Hide[/mwcard]

[mwcard=MW1E32]2 x Regrowth[/mwcard]

[mwcard=MW1E12]1 x Divine Protection[/mwcard]

[mwcard=MW1E17]1 x Force Orb[/mwcard]

[mwcard=MW1E29]5 x Nullify[/mwcard]

[mwcard=MWSTX1CKE04]3 x Enchantment Transfusion[/mwcard]

[mwcard=MW1E21]2 x Hawkeye[/mwcard]

[mwcard=MW1E31]1 x Poisoned Blood[/mwcard]

[spellclass]Equipment[/spellclass]

[mwcard=MW1Q06]4 x Dragonscale Hauberk[/mwcard]

[mwcard=MW1Q08]1 x Elemental Wand[/mwcard]

[mwcard=MW1Q19]3 x Mage Wand[/mwcard]

[mwcard=DNQ09]2 x Wand of Healing[/mwcard]

[mwcard=DNQ07]2 x Veteran's Belt[/mwcard]

[mwcard=MWA01Q04]1 x Leather Chausses[/mwcard]

[mwcard=MW1Q16]1 x Leather Gloves[/mwcard]

[mwcard=MWSTX1CKQ06]1 x Eagleclaw Boots[/mwcard]

[mwcard=FWQ01]1 x Dancing Scimitar[/mwcard]

[mwcard=MW1Q22]1 x Moonglow Amulet[/mwcard]

[mwcard=MW1Q32]2 x Suppression Cloak[/mwcard]

[mwcard=MW1Q17]1 x Lightning Ring[/mwcard]

[spellclass]Incantation[/spellclass]

[mwcard=PSI02]6 x Dispel[/mwcard]

[mwcard=FWI13]4 x Seeking Dispel[/mwcard]

[mwcard=PSI01]6 x Dissolve[/mwcard]

[mwcard=MW1I28]2 x Teleport[/mwcard]

[mwcard=FWI12]1 x Minor Heal[/mwcard]

[spellclass]Creature[/spellclass]

[/spells]

[cost]Total cost: 120 pts[/cost]

[/spellbook]

TBH, not sure i want the lightning might swap with fire.