Trouble taking down Ilfrit

[Umo]

But being lvl 20, I don't have the gla 3 step combo and I swear to god I used fastblade then savage, when that didnt work i used flash until my mp ran out and it made no difference either way.

Do not wait for the combo to not work. I mean, Fast Blade > Savage Blade > Flash > Rinse and repeat. Pop up your defensive abilities (or even offensive if any) and stick to your aggro combo + Flash. If you run out of MP do not spam Fast Blade > Riot Blade, just use it untill you can cast Flash again, then back to Fast Blade > Savage Blade > Flash > Fast Blade > Savage Blade...
Also, do not forget Fight or Flight + Shield Lob will give you a good chunk of hate aswell.
On the other hand, get Skull Sunder from Marauder (Lv.4) if you haven't already. It helps.

PS. On a side note, I don't know if you're that type of tank, but just in case: please, do not dance around the boss. Please.