The 92-year-old Redstone is battling Herzer's allegations that he is mentally incompetent. Herzer, 51, filed a petition in Los Angeles County Superior Court in November after Redstone removed her from a position of power as the guardian in charge of his advance healthcare directive.
On Tuesday, Redstone's legal team filed a new court document that takes direct aim at Herzer's motives in the legal fight.
"This is a pre-death trust contest dressed up as healthcare litigation," the court document reads. "Under the September 2015 [estate] plan, Ms. Herzer would have received $50 million and Mr. Redstone's Beverly Park home, worth roughly $20 million."
Redstone was executive chairman of Viacom Inc. and CBS Corp. until last week. In October, the billionaire changed his will directed that his former companion, Herzer, no longer was entitled to the money or his compound that overlooks Beverly Hills.
"He instead directed that those assets pass to his charitable foundation at his death," the legal document stated.
Last week, Redstone's daughter, Shari Redstone, filed a declaration saying that she believes Herzer has already received at least $70 million from her father over the last few years.
Herzer attorney Pierce O'Donnell on Tuesday issued a statement that questioned Shari Redstone's motivations and defended Herzer.
"The only reason Manuela is fighting this fight is out of concern for Sumner's well-being and a desire to honor the decisions he made when he was competent to do so," O'Donnell said.
"The people who've been manipulating Sumner — most notably his daughter Shari — are trying to insinuate all sorts of base motives for Manuela's actions, but the fact is that she is one of the only people around Sumner who has consistently put his interests first, which is why they regard her as such a thorn in their side," O'Donnell said.
Herzer has said in court documents that she met Redstone at a dinner party in the late 1990s, and they began a romantic relationship. She said Redstone once asked her to marry him, but she declined.
Several years later, after Redstone's second marriage collapsed, Herzer and Redstone became close friends. Redstone in 2009 bought Herzer and her children another house in Los Angeles, which she still owns.
Herzer's name also is on property records for Redstone's apartment in the Carlyle Hotel in New York. The documents state that Redstone and Herzer co-own that apartment, although in a side agreement, Herzer acknowledged that the apartment belongs to Redstone as long as he is alive.