On the Map 8 - Follow the tunnel all the way to (C-7), where you exit back to the jungle.
There are two Flame Spouts on the way.
Be alert of the Ash Dragon near the end (before the last Flame Spout). It has a wide sight and sound detection range, and will use Draw In. Time it right and you can walk into the tunnel without a problem when it is far enough from the entrance.
G-6 > H-8 > D-12 > J-8 > E-7 > G-7 > C-7
Now that you're in Yuhtunga Jungle again, go to (K-7), through one of the tunnels under the waterfall. Follow the left wall and take the second tunnel.
The headstone is located exactly at the North Western edge of (L-7).
Both will attack the character examining the stone.
It is possible to only fight Tipha, by using Sneak and Deodorize before examining the stone. However, it is essential to wait for the 3 minutes for Carthi to de-spawn before slaying Tipha, or else, Carthi must be slain as well. If Carthi de-spawns after Tipha was killed, re-spawning them may be required.
Gravity and Bind work, but it is worth noting that they easily lose interest if ventured too far from and if not aggravated soon enough, will regenerate HP quickly like any unclaimed monster not engaged on a player character.
If the character who examines the headstone has the effect of Sneak applied, they will not attack immediately. Thus it is possible to complete the objective by only defeating one of them, provided the other has de-spawned before the other is slain.
If the other de-spawns after one of them is defeated, it may be necessary to re-spawn them.
Note that they will attack anyone within hearing range, and detect the use of magic from particularly far distance.
Follow the uncharted path leading towards north, to (I-7) to find the headstone.
The Doomed named Doomed Pilgrims will spawn here when the stone is examined. It is generally regarded as the most difficult of the headstone fights, it hits hard and fast, so be careful. High evasion works well against it.
Somewhere on the island of Zepwell lie the remains of an ancient temple.