The FINAL FINAL boss of FSII

Heyo, everybody! Guess who's back for more boss guides? Time to start off with basic needs:
FULL restock. Downs, Pots, everything ol' merchant dude got.
Immunize Spell
Aegis Barrier Spell
HIGH LEVELLED PARTY. Preferrably 1 rebirth.
Amulet of Hope (You'll get this no matter what, but hey, not like you know how to use it.)

Now, you're thrust into a battle vs. Horntail's three heads and Hein. Now...WHAT?! ELEVEN MINUTES?!
That's right, you get 11 minutes to beat this buttmunch.
Horntail can bite (Can miss, but does a crapload of damage if hits sometimes) cast Cold Wind (Bye bye all of SR~) DARKNESS POSSESSION (Immunize...?) PARTY POISON (IMMUNIZE?) and...Dispel. Ew.
Hein himself...Well, he has a SUPER POWERFUL OMEGA DRAGON CRUSHER that his for around 1.5k unbuffed. He also has something called the "Hei-an stance." Lol Heian. But wait, THIS IS YOUR CUE TO USE THE Amulet of Hope. Because if you don't, he'll use "Despair: "Miserable Fate"" Which...Is an insta kill. Yum.
If you use the amulet, the attack will only do 1 damage. Woot. He also does Darkness Possess. Moving on...
I suggest you blast Hein first. Life's a lot easier without those danged Spearcrushers landing on you. I even have proof.
Time 1 of beating this guy: 2 minutes left on clock
Time 2: 7 minutes left.
The first time I killed Hein last.
The second time I killed him first.
Wait! myfantasy says that Hein can be affected by various status effects! I dunno, try it out.
Wait again! myfatnasy confirms that Zeru changed that! Ha-ha, no respite for y'all~
After that, Horntail should be hideously easy with Immunize and Aegis Shield. Just watch out for time.
..Hm, that's all.
ALSO! If you're slow enough so that Hein can go twice in a row, you might as well kiss your butt goodbye. Make sure at least one character is FAST!
While I'm at it, I'll give you a tip for the ending.
"Sometimes, the hardest thing to do is to stand aside."