Megaflare

Mega Flare, also known in some cases as Sun Flare, is a recurring attack in the Final Fantasy series. It is normally a very damaging move used by the summon Bahamut, but as noted, it is occasionally an ability of another boss.

Final Fantasy IV
Brachioraidos, a Superboss, borrows a page from Bahamut by using a count-down Mega Flare attack. The dragons Dark Bahamut and Lunar Bahamut also cast the spell.

Final Fantasy V
The boss Twintania is fond of retaliating with Mega Flare after being struck with a magical attack. The party can also Catch the Prototype to use Mega Flare.

Final Fantasy VIII
Dark Flare, an upgraded version of Bahamut's Mega Flare, is used by the boss Tiamat who in itself resembles Bahamut greatly.