Tribal Island

"The game-changing Tribal Island is here! Just as the last of the Rare monsters was revealed, this extraordinary new realm sprang into existence and ignited a new challenge for novice and seasoned players alike. It's up to you to form a Tribe with your Friends and keep your monster well-fed to raise your Tribal Level, earn Starpower, and redeem Tribal Rewards. You may even unlock "an ancient secret of the monster world!"

About
Tribal Island was introduced on August 6, 2015 as part of update 1.3.5.

This Island is a collaborative effort between you and up to 29 of your Friends, who form a Tribe. Each friend can contribute one Monster (a "natural" single, double, triple, or quad-element type) to the Tribe's harmony. As the monsters of the Tribe are fed to higher levels, the Tribe as a whole reaches weekly Goals and is rewarded at the end of the week.

It is available for free when the map becomes available at Level 10.

Indigenous Monsters
Similar to Gold Island, the Monsters of Tribal Island are of all elements, but only natural monsters are on Tribal Island. Additionally, every member of a tribe must contribute one natural monster to the island.

Rocks and Trees

 * Main Article: Obstacles

There are no rocks and trees to clear on Tribal Island.

Castle Upgrades
Unlike any other island, Tribal Island does not have a castle, but instead has a limited amount of spaces for people to join your tribe.

Help page
Welcome to Tribal Island!

Join together with your friends to create a Tribe and unlock an ancient secret of the Monster World!

'It's up to you to make sure your monster on Tribal Island stays well-fed so it can earn Starpower! At the end of each week, your Tribe's total Starpower will be collected and credited towards Tribal Rewards for all members to enjoy!'

Get started by seeing which of your friends are already members of a Tribe.

History
A graphic from the in-game News provides a brief history of Tribal Island in monster script. Translated, it reads:

"At one point in history, few could have foreseen the formation of Tribal Island. After all, the Colossals and their island hosts were fated to go their separate ways, never to rejoin... Were they not? The advent of Tribal Island represents the fulfillment of a prophesy from primitive times, in which greater bonds than ever before will be forged between caretakers of the monster realm. And harmony will once more be achieved." If the "Colossals" are the giant monsters on whose heads the islands are built, then Kayna must be one of the "island hosts".

Joining an Island
To begin, select the Tribal Island from your island map. You can then press the "Tribal" button. The Tribal menu contains three tabs: "Tribes", "My Tribe" and "Top Tribes". On the "Tribes" tab, you can see information about your friends' tribes, visit them, request to join one, or accept an invitation to join one. Alternatively, you can use the Tribal menu to create a new Tribal Island and invite others to it.

A maximum of thirty players can occupy a single Tribal Island. Since there are thirty different natural monsters, any duplicated monster will make it impossible to get the complete choir without replacing one of the duplicates.

You must leave one Tribal Island before you can join another. Be aware that whenever you leave and join a different Tribal Island, your monster's is reset to Level 1.

Each player chooses one (and only one) of the natural monsters for the island. You can only choose from the natural monsters that live on one of your own islands. (For instance, you can't choose a Quarrister if you haven't bred one on Earth Island yet.) That monster is then fed to higher levels using food, coins, shards, or diamonds. Monsters on Tribal Island can be fed above Level 15; there does not appear to be a maximum level, although monsters do not grow any larger after Level 15.

Goals
Each Tribal Island has its own Goals that can be achieved in return for diamonds. When a Tribe member feeds his or her monster to a higher level, the overall level of the Island increases as well. Rewards are distributed among every member of the Island at the end of the week.

Goals are achieved when the Island as a whole reaches Level 30, 50, 100, 150, 300, 450, 600, 750, 1000, and 1500. (Note that if a Tribe has the maximum of thirty monsters, it reaches Level 30 automatically, while Level 1500 is possible if each monster is fed up to Level 50.)

When the Island reaches Level 100, the Kayna monster is released from the amber crystal in the center of the Island and joins the harmony.

At the end of each week, all Tribal Island monsters are reset to Level 1 and the Tribal Island goals are reset.

Feeding
Monsters can be fed with diamonds, shards, coins, or food. The cost for each feeding is determined by the following formulas:
 * FeedFoodAtLevel(X) = 250 * X * (X + 4)
 * FeedGoldAtLevel(X) = 10 * FeedFoodAtLevel(X)
 * FeedShardsAtLevel(X) = Floor(FeedFoodAtLevel(X) / 1000)
 * FeedDiamondsAtLevel(X) = Max(1, Floor(FeedFoodAtLevel(X) / 3750))
 * Level Shard Step (L) = L+(L/2)² (-1/4 if odd Level)
 * Shards To Next Level (L) = L² + 4*L (-1 if odd Level)
 * Shards To Level (L) = L³/3 + 3*L²/2 - 7*L/3 (+1/2 if odd Level)

Leveling Up
Shards are the most cost-effective feeding method for levelling up monsters.

Observations:
 * Raising your monster from level n to level n+1 costs 1000*n*(n+4) in food, or ten times as many coins.
 * If levelling with gold, the cost to reach level 27 (76,050,000) is higher than buying a Wubbox (at regular price).
 * The best shard to diamond ratio is reached when all 30 island players level their monsters to 50 with shards. Each one would spend 45300 shards and get 20 diamons in return, a 2265 shard per diamond ratio.
 * Reaching level 50 by feeding only diamonds would require 12,020 of them.  Buying that many diamonds through the app store would cost over $400 USD.

Starpower
Starpower is a separate score for each individual player, but it is earned by participating in Tribal Islands. At the end of the week--at the same time as Rewards are distributed for reaching Tribal Goals--every Tribal Island member's Starpower score will increase by the final level of the Tribe. Just like the diamond rewards, the higher the Tribal Island level is, the more Starpower is awarded to all of its members.

An individual player's Starpower accumulates continuously from week to week, and does not reset when leaving a Tribal Island or joining another.

It is not yet clear whether Starpower will be used anywhere else in the game.

Strategy
Monsters do not earn Currency on Tribal Island. However, players do earn diamonds at the end of the week if the Tribe as a whole achieves certain Goals.

If you decide to join a tribe, it's up to the tribe chief to accept your request. You can improve your chances if you follow these guidelines:
 * 1) Pick a monster not yet in the tribe. Many people would like to hear the whole song and that can't happen if some monsters are missing.
 * 2) If you have requested to join a tribe, check back frequently to see if you've been accepted. Popular tribes have many requests to join. If your request is not accepted for several days, cancel it and try a different tribe.
 * 3) Contribute to the tribe by feeding your monster weekly. Don't give the chief a reason to remove you from the tribe.
 * 4) Shards are a good way to level up your monster once you are earning heavily on Ethereal Island. A full Ethereal Island with level 15 monsters will allow you to level-up on Tribal Island to 100 or more in a week.

Assuming that all tribe members are using shards to level their monsters, there is a point where it is no longer cost effective to keep leveling up, since 30,000 shards can be traded for a diamond in the market. Using this fact, the following table shows what individual levels need to be reached to meet tribal goals. Blank spaces in the table mean that it would cost more shards than it is worth to reach the next goal. For example, in a one-member tribe, it takes 35,020 shards to go from level 30 to level 50 to gain a 1 diamond reward, which is more than the 30,000 shards needed to buy a diamond in the market.

(Note that the higher levels are projected based on patterns found in the "leveling up" table.)

Teasers

 * Since the appearance of the Rare Mammott, BBB began posting letters on social media and in-game news as hints. The letters together spelled out "Tribal Fire".
 * On July 21st, BBB posted a video on their vine with the woman that voices the Pompom singing "C'mon let's go".
 * On July 24th, BBB posted another video on their vine with a man singing a song similar to Furcorn.
 * On July 27th, an in-game loading screen message read "Join together with your friends to create a Tribe, to discover an ancient secret about the Monster World on Tribal Island."
 * On July 28th, BBB posted another vine with a woman singing similar to Maw, and confirmed that an announcement will be arriving "later this week".
 * Also on July 28th, a post that included a secret message between 2 Tweedles appeared. It said, "Hey! The monster handlers are working on something. Tell everyone." The other Tweedle responded, "OK! I'll tell them!" The game servers then went into maintenance for several hours.
 * On July 31, BBB posted a trailer for Tribal Island on Youtube, Facebook and Twitter that showed the Kayna singing.