Fragment of Seren

The Fragment of Seren is the final boss of Song of The Elves.

I struggled to defeat the Fragment of Seren for a while. I attempted the fight using both the phoenix necklace method and blood spells with blood bark with a magic level in the high 80s. After many failed attempts, I decided to train my magic up higher to be able to use blood barrage and eventually defeated the fragment somewhat more easily with supplies left over at 95 magic.

First of all, you will want to death pile everything except for the gear and supplies you need, and set a 1-hour timer to get them before they despawn. I recommend using anglerfish (82 fishing and 84 cooking), some other higher healing food (like sea turtles from Tempoross), and blood barrage (at least 94 magic) with blood bark armor. The fragment's phase 4 attack will kill you unless you are at or above maximum HP. The two ways to counter that are to use anglerfish which can heal you above your max HP or the phoenix necklace method. Equipping a phoenix necklace and consuming a nightshade (which is a stackable item) to proc it to heal you makes you invulnerable for the phase 4 attack. However, this requires you to maintain your HP just above that proc threshold, which I don't think is viable with also using blood spells. During the phase 2 attack, especially later in the fight, the multiple copies of Seren hitting you at once is very dangerous while you are maintaining your HP in that range to be able to proc the phoenix necklace and trying to conserve supplies. For this reason, I recommend the blood spells/anglerfish approach over phoenix necklaces, which I was not successful with. If you want to try the phoenix necklace way, gem bags from mining stars are a good way to source the diamonds.

This was my inventory for my successfully beating seren: 

My approach was to first get noted sea turtles from Tempoross and noted super restores from decanting at the Grand Exchange. Store everything in your looting bag and get your cooked anglerfish together. Then death pile in Lumbridge basement and start a 1-hour timer. Pick up the noted sea turtles and noted super restores and unnote/cook what you need. Then death pile a second time, pick up your gear and supplies carefully, and run to Port Sarim. If you took any damage from bugs in the Lumbridge basement, use the food shop there to heal. Take the charter ship to Port Tyras and make your way through Isafdar to the Underground Pass to start the fight. To get back to Lumbridge, I used the Ring of the Elements water altar teleport. For switching to Ancients on a clunky inventory, you can use 1 inventory to buy a Shantay's pass, take the carpet to the bandit camp, and buy a waterskin (4) there instead of Shantay's pass and can be accomplished easily without heat damage.