Complex sentence: However, Supergirl was eventually able to fight off Grodd's influence thanks to some outside sources, allowing her to oppose Grodd until the sun was restored, Grodd being seemingly killed when an icicle fell into him.
Split into simpler sentences: However, Supergirl was eventually able to fight off Grodd's influence thanks to some outside sources, allowing her to oppose Grodd until the sun was restored. Grodd was seemingly killed when an icicle fell into him.