Since I started playing D&D back in 3.5, we always encouraged lateral thinking: He's wearing full plate armor? Shocking grasp, since metal loves conducting electricity! (DM gives a +1-2 to damage) It's raining and the enemy is soaking wet? Frost spells bite harder! People get a penalty to Dex as their clothing freezes! He's wearing chainmail (or plate armor again)? Heat metal! People climbing a wall to get to you? Gust of Wind! They have to make Str (or Dex, whichever's better) checks to avoid losing their grasp and falling!