Greetings, Frolly!
Thank you for posting your concerns about your game crashing while you tried to enter the Ifrit battle. In order to make sure that we have sufficient information for a thorough investigation, it would be a great help to us if you could provide the following details:

Platform:
ISP:
Type of Internet Connection:
Internet Connection Speed:
Date & Time:
Frequency:
Character Name:
Race:
World:
Class/Skill Rank:
Area and Coordinates:
Party or Solo:

In addition, you may want to try to contact the the SQUARE ENIX Support Center, just in case they may be able to help you find the source of this trouble that you are experiencing. Thanks again for your participation!