The Camp of Qetesh & Resheph is located in the middle bottom of the Uab Nome territory just above the Desheret Desert in the very south of the World Map.
It is 1 of 4 Elephant locations where you need to fight elephants to complete the locations, which will be necessary if you are going for the Old Habits achievement, and it is the only elephant location where you fight two elephants at once, where starting out one is always trying to melee you and the other is trying to range attack you, and they don't do friendly fire to each other
All elephants are lvl 40 and will insta-kill you with their attacks if you do not pass some sort of check, whether through also being lvl 40 or by upgrading your gear/breastplate enough so that you have enough HP
As a reminder, there are no difficulty achievements for this game, so it is okay to switch to Easy to complete this fight for the achievement if you want to get it done.
You can also upgrade your bows/swords/shields to your current level at your local blacksmith for a large chunk of gold, which is worth doing if you are lvl 40 and have a lvl 22 legendary with a cool extra ability
All of the elephants are level 40 and have two different modes, melee or ranged. When they come in to melee you I found the best tactic was to dodge around behind them and melee their back legs whilst avoiding their stomp attacks, but this can be sketchy because there are times you seem to be able to dodge everything and times when the elephant hits you anyway. When they do ranged I would pull out the light bow for the rapid fire on their legs which does just as much as your melee attacks and also builds your adrenaline bar which will allow you to occasionally use your adrenaline attack using RT + RB.
Any bow would work, but the light bows are the most efficient, next with the hunter bows, predator bows and warrior bows, in that order based on balancing how close you might be to the elephant during the duration of the fight and the amount of ammo you can carry with picking up the infinite ammo drops during the fight.
I was using the Composite Bow for these fights, which is the best light bow in the game obtained from killing one of the Phylakes. Legendary weapons in general will help. Here is a list of the Phylakes drops:
The Outsider (drops Golden Wolf, a sword that gives Health on Kill)
Ptolemy's Fist (drops Copper Mace, a heavy blunt that gives Health on Hit)
The Iron Ram (drops Smoke and Mirrors, a predator bow that is On Fire)
The Stranger (drops Sarissa, a spear that gives Health on Damage)
Ra's Mercy (drops Storm Blades, dual blades that have instant charging)
The Hill (drops Headsplitter, a heavy blade that gives Health for Critical)
Bane of Hathor (drops Deathstorm, a hunter bow that is On Fire)
Half-Horn (drops Composite Bow, a light bow that gives Health on Hit)
The Iron Bull (drops Djoser's Pride, a shield that gives Sleep on Block)
The Galatian (drops The Fourth Plague, a warrior bow that gives Health on Hit)
If you're having trouble fighting the Phylakes, again, switch to Easy if you're not already there. Similarly, it is recommended to use Hepzefa's Sword, a legendary sword with the On Fire ability that you obtain from completing the main quest The Final Weighing. The On Fire ability is the only status that has any significant effect on the Phylakes. If you dismantled Hepzefa's Sword by accident you can buy it again at the Bureau of the Hidden Ones
You may not get your legendary weapons at 40, so the weapons might not be level 40, but again you can go to a blacksmith and pay to level them up to 40 for maximum efficiency.