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 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 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). 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. As his rage increases, Telos also begets new mechanics, and the health of him, his golems, and the fonts increase slightly. 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 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.

If the player "chains" their loot and dies in subsequent kills, they will retain part of the loot they had upon death. This starts at 1 killstreak at 5% of the loots, and maxes out at 15 killstreak for 75%. Note that this applies only for stacked items, and not the total loot itself; if the player had one uncut onyx in their "chained" loot when they died, they will lose that uncut onyx; however, if they had 4 and died at a 15+ killstreak, they will keep 3 of the onyxes.

Telos's drop tables are aligned with three different reward levels: bronze, silver, and gold. The silver drop table is unlocked after successfully killing Telos at 25% enrage, and the gold is unlocked similarly at 100%. Telos's enrage upon his death will determine what grade of loot the player will obtain: All collected rewards are automatically deposited into the player's bank before leaving the confrontation. Collecting all unclaimed rewards will reset the player's kill streak and reduce Telos's enrage level back to 0%.
 * Bronze
 * The bronze reward table is given for players who kill Telos at 0–24% enrage.
 * Silver
 * The silver reward table is given for players who kill Telos at 25–99% enrage.
 * Gold
 * The gold reward table is given for players who kill Telos at 100% enrage or greater.

Should the player decide to continue their encounter with Telos, their unclaimed rewards will be held in the Trove of Telos and they will be presented an additional wheel in order to determine the percent which Telos's enrage level will increase (a random, whole-number value from 5 to 20). If the player decides against continuing their confrontation afterward, they may claim their uncollected rewards at any time from Soothsayer Sybil or the font on the initial platform before beginning their next fight with Telos.

After the percent which Telos's enrage will increase has been decided, the player may leave and initiate another confrontation with Telos to continue the challenge - beginning the kill streak mechanic. (Note: Leaving the Heart of Gielinor to refresh your supplies, lobbying, or logging out will not reset your kill streak, so long as you have not entered another instance and initiated combat with Telos once again before doing so.) The aforementioned process may be repeated until the player collects their rewards, or up to a maximum kill streak of 200 - upon which the player will be notified with a message in their chat box requesting that they claim their rewards before confronting Telos once more. Once the player has collected their rewards, their kill streak will be reset to 0, and Telos's enrage level will return to 0%.

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; it follows a mechanic like the Volcanic shard instead.

Other
The type and quantity of the rewards is dependent on the player's killstreak and Telos's enrage percentage.

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 to those that disconnected during the fight. If the player has a killstreak and dies/leaves while fighting Telos, they will keep anywhere from 5-75% of their 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.