Melee works, but only if you really focus on it to the exclusion of everything else (most other character types you can divide into two focuses, like stealth/archer, but diverting attention from pure melee to anything else seems to just gimp melee). It also doesn't really fit in with the ethos of using the environment or terraforming the environment mid-battle with magic, since then you're just going to splatter your melee character with the enemy.
I use my archer to soften up the enemy at range (and Ricochet to deal out multiple hits) whilst my main mage slows them with oil slicks and then blows up said oil slick with fire (which can also slow them down), then my secondary mage (Jahan) shocks them with lightning. For fire-based enemies I switch to a Rain/Lightning combo which has the same effect, or just free them. Medora I keep in reserve for when the enemies reach the party, which hopefully is rarely. Also having her stand out front means she acts like a damage soak, with potions and the two mages able to keep her going.