Ascension shard

Ascension shards are received from killing monsters in the Monastery of Ascension. 100 shards are required to create an ascension crossbow or its off-hand variant, along with a dragon crossbow and all six ascension signets. At level 90 Fletching they can be fletched into ascension bolts.

At 92 Fletching, 25 shards can be used with one set of Ancient bones at the workbench of a player-owned port to create a set of 25 Death lotus darts or their off-hand variant.

One way to obtain these without buying them is to hop worlds and pick them up from players killing the Order of Ascension creatures.

Trivia

 * Fletching ascension shards into bolts is one of the fastest methods of training Fletching, having rates of over 600,000 experience per hour, albeit at a high cost.
 * With the update on 24 June 2013, the buy limit for this item on the Grand Exchange increased to 10,000.