ferocious

In some of the avataras of Vishnu such as

1. Sri Narasimha Avatara, Sri Boovaraha Avatara, Sri Matsyavatara, Sri Kurmavatara, after the enormity of the avatara, Sri Vishnu was too 'ugra' or 'ferocious' and unable to assume his former self. 
2. At this juncture, Lord Shiva is said to have assumed forms that brought forth a battle between huge Vishnu form and himself at the end of which Shiva is said to have cooled down Sri Vishnu.