Spirit terrorbird

A Spirit terrorbird is a familiar that can carry up to 12 items and restore run energy with its special move, Tireless Run. It requires a Summoning level of 52, but has a relatively low pouch price for its level. As with most Beasts of Burden, it cannot hold untradeable items, items that are deemed "too valuable", and Rune essence or Pure essence.

Once summoned, Spirit terrorbirds will disappear after 36 minutes, dropping all of their inventory. Players will be alerted when one minute remains, then when 30 seconds remain before the Spirit terrorbird will disappear. A Spirit terrorbird can hold up to 600,000 coins in items, none of which can be worth more than 50,000 coins, allowing it to hold 150,000 more coins in items than a bull ant familiar.

The next beast of burden is the War Tortoise at level 67 Summoning. Players are recommended to use the Spirit terrorbird if they do not need the high capacity of the War tortoise due to the significantly lower cost of the Spirit terrorbird.

Spirit terrorbird pouch
A Spirit terrorbird pouch is made by using a Summoning pouch on a Summoning obelisk with twelve spirit shards, one gold charm and raw bird meat. Making one pouch earns 68.4 summoning experience. Using a pouch to summon a Spirit terrorbird gains 0.8 experience, and costs 6 Summoning points. If Spirit terrorbird pouches are exchanged at Bogrog, players will receive 9 spirit shards per pouch.

Tireless run scroll
A Tireless run scroll enables the use of the Tireless Run special move for Spirit terrorbirds. Using a Spirit terrorbird pouch on a Summoning obelisk creates 10 Tireless run scrolls.

Tireless Run
Tireless Run is a special move for Spirit terrorbirds which restores running energy by half your Agility level rounded up, and temporarily increases the player's Agility level by 2. The Agility boost from the tireless run scroll does NOT stack with that of an Agility potion.

Tireless Run is useful when players have to run for long periods of time, such as during the Summer's End quest, or while doing a special task such as an Agility course or the Pyramid Plunder activity, where players have to do a lot of running in short periods of time. Another location useful for this is the Wilderness. However, familiars are prohibited from entering certain places where unlimited run can be useful (such as the Ape Atoll Agility Course, Dorgesh-Kaan Agility Course or Brimhaven Agility Arena). Some players find Tireless Run useful when Runecrafting, particularly when using the Ourania altar or running Astral runes. However, this cannot be used when runecrafting law runes, because familiars are not allowed on Entrana. Tireless Run is also commonly used for Penguin Hide and Seek due to the run boost.

Tireless Run is essential when attempting to solo in the Saradomin chamber of the God Wars Dungeon, as Zilyana moves very fast, meaning you have to run constantly.

Trivia

 * The Spirit Terrorbird almost identically portrays an artist's impression of Brontornis burmeisteri, a prehistoric predator that lived between 62 and 2 million years ago, and was also nicknamed the 'terror bird' due to its scary appearance.
 * The Spirit Terrorbird will still say 'so... heavy...' if it is carrying 12 weightless items, such as runes.
 * Despite being better than the bull ant familiar in every way minus the required summoning level, terrorbird tertiary ingredients (and thus pouches) are far less expensive - ants require marigolds, compared to the terrorbirds' raw bird meat. Marigolds are farmed and collected 1 at a time and are expensive, whereas bird meat is far less expensive and can be collected in large quantities from hunter or Chargurr in Oo'glog.

Spirit terrorbird Spirit terrorbird