Many years ago before Valve released DotA 2, the company had filed for a trademark for DotA 3. The trademark was filed alongside DotA 2 which seemed to indicate that Valve had plans for a possible sequel. However it looks like Valve has since abandoned the DotA 3 trademark, according to the United States Patent and Trademark Office. The USPTO has since classified the trademark as “abandoned because no Statement of Use or Extension Request timely filed after Notice of Allowance was issued.”