Reed the Strategy
To obtain this achievement you need to finish the Oracle in under 25 minutes, if you want to knock out 2 birds with 1 stone you can follow the guide below to also unlock the achievement below this paragraph. If you only want the Par time, just do no skulls and on easy difficulty following my guide, run past all enemies you can using invisibility or you can probably even get away with just running past them.
For this mission I felt any difficulty higher then normal was unneeded. I finished this mission with 47,000 points in 19:29 netting the par score and par time achievement. Follow my guide and you can do the same!
Skulls: Catch, Famine, Fog, Jacked, Streaking, Thats Just... Wrong
A key thing to remember while doing this is kill quickly and run quickly to where you need to go. You will be sword most enemies and ignore many others. There will be 2 slow parts, first is the lift in the beginning, then there is the flood infested room you cannot proceed forward right away, at these 2 points just kill everything you can and survive.
Use plasma rifle on flood for health/shield and when on the lift just plasma rifle sentinels sword flood as needed, and don't forget melee the containers on the lift for health/shield with your plasma rifle, those keep coming so you can have max shield the whole lift.
When you get to the flood infested room just keep killing flood and shoot the little ones with your plasma rifle if you need health. Also there are 2 swords with 100 ammo on the ground save 1 for when you are able to leave the room.
Once you get out of the room just kill the enemies as needed with your new sword. Do not worry about the ammo, try not to use it on the grunts though. When you get to the room where there heretic is running from you, you want to quickly go to the door he goes in and kill everything while going there.
After the cut scene grab a new plasma rifle from one of your allies (there should be a carbon or something on the ground to replace your current plasma rifle, and give your sword to the elite with a plasma rifle. Then take your carbon/other weapon and trade it with the sword on the white elite giving you a new sword and a new plasma rifle with full ammo and proceed forward.
Going up to the lift make sure to kill flood with your sword and sentinels with your plasma rifle. When you get to the top quickly cut the 3 cables starting with the one in the back (facing the buttons on the elevator) then the one to the left of the buttons, then the final one and grab the new sword on the ground (they are just everywhere waiting for you). Proceed back down.
While back tracking the previous level make sure to use your sword on any flood, kill grunts quickly (I threw plasma's) and if needed kill some carrier flood for health shooting all the little ones with your plasma rifle. When you get into the banshee don't even do anything but fly to the marker. Also watch out for any Plasma's while you are near explosive objects, that would be a disaster to have them blow up when you are next to them. While going to the final room make sure you have your shield up as much as possible because you will take a bit of damage in the final room, nothing compared to Heroic or legendary though.
Once you get to the heretic, if you need a new sword head left and there will be one on the ground. He is extremely easy, just slice him and his clones to pieces. It will take 2 hits with a sword to finish him.
Good luck and have fun