Originally Posted by Silverlance
Safer's script is MUCH shorter than Bizarro (which is the longest in the game, if you count the 3 different parties.) Many scripts behave like Bizarro's in that they maintain a count of some kind and execute commands in an order. I've left out some unimportant script commands, like his death counter (which basically has him using his death animation then being removed from battle.)
Setup Phase
-- If KotR was used on Jenova, Sephy gains an 80,000 HP bonus.
-- Every character, excluding Aeris, at level 99 will add to his HP, attack, defense, m. attack, and m. defense.
-- Everytime a Head part on Bizarro Sephiroth was killed, 100 HP are deducted from Sephiroth's base HP (up to 250 times.)
-- Turn Count begins at 0 (this is not in the script, but it's implicit.)
Main Phase
-- Sephy's MP are restored to full.
-- Turn Count is increased by 1.
-- If Turn Count = 1...
-- -- If Sephiroth has "SLOW" status use DeSpell on self.
-- -- Otherwise if Wall was used cast DeSpell on all party members and reset Wall Used variable.
-- -- Otherwise, case Wall on self and set the Wall Used variable.
-- If Turn Count = 2...
-- -- If Wall was not used, cast Deen on all party members.
-- -- Otherwise, cast Shadow Flare on a random party member.
-- If Turn Count = 3...
-- -- Use a Physical Attack on a random party member.
-- If Turn Count = 4...
-- -- Fly up.
-- -- Make Sephiroth a long-range target.
-- If Turn Count = 5...
-- -- Use Pale Horse on a random target.
-- If Turn Count = 6...
-- -- Use Super Nova on all party members.
-- If Turn Count = 7...
-- -- If Sephy lost over 3/4 of his health, use Heartless Angel on a random target.
-- -- Otherwise use Break on a random target.
-- If Turn Count = 8...
-- -- Fly down.
-- -- Sephy is no longer long-distance.
-- -- Reset Turn Count to 0.
Turns out I was wrong, he does have Heartless Angel as Safer. Shame on me for not confirming. Anyhow, he'll only use it every 8 turns (on his 7th turn) if his HP are below 25%.