Should I use 'but' or 'and'?

Entering the Portal to the Abyss while the others watched, Caramon began to traverse the vast distance to the battle between Raistlin and Takhisis, but/and encountered the broken body of Crysania where his brother had left her to die. Lifting her in his arms, Caramon returned to the Portal and awaited Raistlin’s inevitable retreat to the world from the onslaught of Takhisis and her minions.