Story to Summon Rotten Stray against Tree Sentinel – Elden Ring

You have to start at Limgrave (starting area).

Mark Dragon Burnt Ruins and go there.

After that, go downstairs in the main area.

And sneak across the Crouch Stance (L3).

You have to open the door and open the chest inside the room.

Then get teleported to Sellia crystal tunnel.

You can grab the loot here, but it is optional.

After that, exit the room and turn right.

Avoid the Miners and follow the path.

If you get shot, then you need to heal yourself.

After that, go down and touch Grace.

Note how far you teleported.

Next, you have to exit the cave and turn left near the water.

You have to get Rotten Stay Ashes.

And then touch the nearby Grace.

Rest at Grace and fast travel back.

After that, equip the Rotten Stray Ashes.

And ride near tree Sentinel.

Now you will need to call Rotten Stray.

Ride Around (enemy shield side safe).

You have to get a hit in (it is optional but recommended).

Wait for summon to poison tree sentinel.

Tree sentinel poisoned will slowly die.

After that, you have to run to the safe platform.

Wait for tree sentinel to lose all health.

If he goes away you can lure him back.

If you hear Glang noise, he teleports.

You have to go find a tree sentinel so you see him die.

Once he dies, you will get Golden Halberd.