Complex sentence: With Brain and Scamper's help, he assembles a huge, monstrous being from human remains, but when he brings her to life, he discovers that the "Evil Bone" he gave her was not activated, making her gentle, affectionate, and feminine.
Split into simpler sentences: With Brain and Scamper's help, he assembles a huge, monstrous being from human remains. However, when Igor brings her to life, he discovers that the "Evil Bone" he gave her was not activated, making her gentle, affectionate, and feminine.