Complex sentence: At WrestleMania 23 in 2007, Undertaker became the contender to Batista's World Heavyweight Championship after winning the Royal Rumble and then he delivered Tombstone to the then-champion Batista to get the victory and his first World Heavyweight Championship.
Split into simpler sentences: At WrestleMania 23 in 2007, Undertaker became the contender to Batista's World Heavyweight Championship after winning the Royal Rumble. He delivered Tombstone to the then-champion Batista to get the victory and his first World Heavyweight Championship.