Telos, the Warden

Telos, the Warden is a solo-only boss that is intended for players with a high combat level. He is an elemental born from the Anima Mundi who guards and protects the Heart of Gielinor. He is billed as the toughest solo boss monster in RuneScape. The boss is accessed by entering a tree in the central area of the Heart of Gielinor. Players are able to attune a portal in the Max Guild to access Telos.

To fight Telos, players first must obtain an ancient sigil. The four components of the sigil can be obtained by killing all the generals in the Heart at least once; therefore, there is a minimum of 80 Attack, Prayer, Magic and Ranged required to reach Telos. The components are always a guaranteed drop, but only appear to the person who dealt the most damage to the boss. Once used on the door in the middle of the dungeon, it will be consumed and give the player permanent access to the boss chamber.

Killing Telos is a possible Soul Reaper assignment. The assigned number of kills can vary between 2 and 8.

Telos is one of the bosses required to unlock the The Reaper title, which is a requirement for the untrimmed completionist cape. Defeating Telos at a minimum of 100% enrage or greater is a requirement for the trimmed completionist cape. Upon killing Telos at 500% or more enrage, players unlock the Warden title.

The music track Anima is unlocked by entering Telos's arena.

Strategies
While fighting Telos at under 100% enrage, the player will progress through four phases, each of which - upon successful completion of the phase - involve Telos and the player gradually descending down platforms into the Heart of Gielinor. If Telos is encountered at an enrage level of 100% or greater, the fight is extended to five phases, the last of which involves mechanics abstracted from all four phases preceding it.

Telos's difficulty is scalable: players are able to choose the fight's difficulty which affects both the difficulty of the boss and the value of rewards received from killing the boss. To do so, the player must successfully defeat Telos at an enrage level greater than 0% (see below). Then, when initiating a confrontation with Telos, the player will receive an interface in which they may select a custom enrage level (between 0% and the highest enrage level on which they successfully scored a kill plus 5%). Players can obtain all of Telos's unique drops at any enrage, but the chances of getting one increase with higher enrage.. As he gains enrage, his combat level, life points, and damage inflicted increase. The life points cap at 600,000 points at 200% enrage for the first four phases. Phase 5 caps at 200,000 life points at 300%, which gives Telos a maximum of 800,000 life points. Telos starts using more mechanics as his enrage increases, which also increases the amount of damage they can deal. The maximum possible enrage is 4000%.

There are global broadcasts for the first player to reach 100% enrage and every 100% increase in enrage after that. The first regular and hardcore ironman players to unlock the Warden title were also globally broadcast. Players should be able to defeat Telos initially using the tier 85 Anima Core armour as it will begin with a difficulty comparable to that of a challenge mode fight with a Heart general.

Drops
Telos follows a special drop mechanic; upon obtaining loot, the player can either claim it or "chain" it to increase their chances of getting better rewards.

Upon defeating Telos, a large beam of anima will erupt from the hole he fell into. Upon interacting with the beam, the player is shown a reward for their efforts. The player can "spin" the wheel for a reward, even though it is already pre-determined; a streamlined option is available to skip this feature.

Telos' loot is directly affected by the player's killstreak and how high his rage was. For example, a player starting on a 100% killstreak would get common rewards similar to killing Telos on any other enrage. While Telos' unique drops can be given at any enrage level, the chances of one appearing greatly increase when defeating him in encounters of 100%+ enrage.

Telos has three different "tiers" of loot:
 * Bronze (0-24% enrage) - lowest value rewards and lowest chance of obtaining unique drops
 * Silver (25-99% enrage) - higher value rewards and slight increase of obtaining unique drops
 * Gold (100%+ enrage) - even higher value rewards and higher chance of obtaining unique drops (presumably they start following a normal drop rate)

There is also a challenge option for those who wish to continue the fight with Telos. Another wheel will appear with random numerical values ranging from 5-20%; this wheel can also be removed with the streamlined option. The challenge option "holds" the rewards for the player, and they cannot be claimed until the player defeats Telos again.

After the percent which Telos's enrage will increase has been decided, Telos will start the fight with that enrage. Subsequent challenges continue to stack the newly added enrage onto Telos' current enrage, up to a total of 4000%. The player can either continue fighting Telos with their current inventory, or if needed, return to a bank and restock on supplies. Leaving the Heart (or lobbying/logging) will not cause the killstreak to reset, as long as the player did not start a fight with Telos again. The challenge process can be continued until the player claims their rewards, or if they get to a killstreak of 200. If the player attempts to defeat Telos more than 200 times in a given killstreak, the game will prevent the player from fighting Telos until they claim their rewards. Once the player claims their rewards (either through victory or defeat), the killstreak ends and Telos' enrage resets back to 0%.

Should the player accidentally leave the chamber without interacting with the Trove of Telos, the dormant font of anima in the "lobby" area of his chambers will activate, allowing players to collect rewards or increase enrage.

Unique
The drop rate of the unique items (excluding pet) is dependent on Telos's enrage and if the player is attempting a killstreak. The bronze and silver drop tables have a significantly rarer drop rate for these items, while the gold drop rate uses the normal drop rate. Telos's tendril is not included in the rewards interface; as it is picked up in a manner similar to the Araxyte pet and Volcanic shard and uses the drop threshold system instead.

Other
The type and quantity of the rewards is dependent on the player's killstreak and Telos's enrage percentage, and thus this table is likely to be incomplete.

Trivia

 * A new solo boss monster was first mentioned at RuneFest 2015. Concept art from Runefest showed a boss fight taking place underwater, however the underwater concept was later changed to the fight taking place in the Heart of Gielinor.
 * is the Greek word for purpose, aim, end, goal, or objective.
 * Upon release, there was a glitch/bug where with damage scrimshaws, it was possible for Telos to drop to 0 life points, "killing" him early. This would result in the player being unable to proceed further. This has since been hotfixed.
 * When successfully defeated by a player, the following message is displayed in the player's RuneMetrics event log: "I killed Telos, the final defender of the Heart of Gielinor." If the player defeats Telos more than once in a gameplay session, the message is changed to "I killed x  Telos, the final defenders of the Heart of Gielinor".
 * For a few days after release, players on a killstreak would lose all of their accumulated loot if they entered the arena and left without waking Telos. This has since been hotfixed.
 * Unlike other bosses that have a timer to record a player's personal fastest kill, the timer for Telos only appears at kills with 100% or more enrage.
 * The patch notes of 18 July 2016 changed the following:
 * Prior to the change, a player on a killstreak lost all of their rewards if they died or left while fighting Telos. This was changed because of how harsh this mechanic was, especially for players who disconnected during a fight. If the player has a killstreak and dies/leaves while fighting Telos, they will keep anywhere from 5-75% of their accumulated loot (1-15+ killstreak).
 * The player used to have to "spin" interfaces to determine their reward and enrage gained. Since it was already pre-determined, a streamlined option was added which will give the player their rewards and how much enrage Telos gains if they choose to continue the encounter.
 * On 26 September 2016, Telos received a combat update which allows him to perform rock fall attacks at any enrage level if he is unable to attack the player. However, players reported multiple bugs, which were fixed on 3 October 2016.
 * Telos would not attempt to melee the player on phase 2.
 * The orbs on phase 4 were already charged. In addition, when Telos is siphoning the fonts, the game would think that Telos is unable to attack the player and would send rocks crashing down on the player's position.
 * On 24 October 2016, Telos received an update for his enrage mechanic. The player can now fight Telos at their highest enrage + 5%. This is to help the player reach higher enrages. In addition, phase indicators were also added on his life points interface so players could know how much damage was needed before the next phase would start.
 * Although Telos's combat level increases with his enrage, his base combat level of 2000 will never change in his right-click menu regardless of his current enrage. In addition, his combat level always stays at 2000 in phase 5 regardless of his enrage.
 * Telos is the only Heart boss that appears in his chamber; the other generals are not found in their respective chambers at all. Despite this, Telos can only be fought in an instance.
 * There is an occasional glitch where upon getting close to Telos, he will attempt to wake but suddenly turn dormant again. This can be fixed by moving away before running next to him.
 * In the Beasts tab, when viewing Telos' "The End" attack, it shows him using it in his phase 1-4 form, rather than the phase 5 form.
 * Although the Behind the Scenes stated that Telos would use all three styles of attack, neither Telos or any of his minions use any type of ranged attack.
 * Although one is unable to lobby once the fight has started, managing to log out will result in the player's death.