Ava's alerter

Ava's alerter is an upgraded version of Ava's accumulator that can be obtained during the Do No Evil quest. Since it requires an Ava's accumulator to obtain, the minimum Ranged level needed to wear this item is 50. The improvement is that it has a better armour rating, along with an increased critical chance. It also gives one free elite clue scroll after completing the quest. Ava's alerter has the highest Ranged critical bonus chance (2.2%) of any item worn in the cape slot, besides the completionist cape and the TokHaar-Kal-Xil and is equal to the max cape. Just like the accumulator and attractor, Ava's alerter doesn't work while wearing a metal body.

In the quest, the player takes a metal crate to Ava in order to get a device that can detect buried metal items. She then takes your accumulator and adapts it to search for exact same metal boxes.

If the alerter is lost it can be re-obtained from Ava by using the 'Buy Device' option and selecting the Alerter. This will get players a new Alerter (for 999 coins and 75 steel arrows).

Toggle
The alerter can be toggled to not retrieve anything other than ammo.

Finding boxes with Ava's alerter
During the quest, the undead chicken in Ava's alerter will squawk with increasing excitement as you get closer to a metal box. One "Bwuk!" means you are standing anywhere between nine and five squares from the box. "Bwuk! Bwuk!" means four, three or two squares. Three squawks means one square, and four squawks means you've found the buried treasure. Dig!

Elite Clue Scroll
The alerter is capable of detecting crates containing a bonus elite clue scroll. There are four possible locations where the elite clue scroll can be found. Each player can find a scroll in one of four locations.

Requirements: Completed Do No Evil, Ava's Alerter (equipped without metal armour in the chest slot), Spade

If your alerter fails to detect anything, move onto the next location. The coordinates in each location appear to be the same for each player. It is confirmed on the Free Elite Scroll thread, that there are other places where they could be found. These have yet to be discovered, so if you find one, add it here.

Isafdar
Start in Lletya. Run west out of Lletya, cross the tripwire, and go through the dense forest to the northwest (not over the leaves). Next, go northeast and hop over the leaves. In the next clearing your alerter should start bwuking. Dig where it bwuks four times just like in the quest. The coordinates for this location are "1 degrees, 31 minutes north, 5 degrees, 5 minutes west" (1.31,5.5). Alternatively, using the Tirannwn lodestone and going north-east is another fast route to this location.

Lunar Isle
The scroll can be found on the southwest part of the island, west of the astral altar and south of the city, slightly west of the little peninsula. Dig where it bwuks four times just like in the quest. The coordinates for this location are 21 degrees 50 minutes north, 11 degrees 7 minutes west.

Iceberg
On the iceberg from the penguin quests. After getting off the boat, run north-west to the giant ice column that you can see on the minimap. It's on the north-western side of the column. Dig where it bwuks four times just like in the quest. The coordinates for this location are 26 degrees, 16 minutes north, 6 degrees, 20 minutes east.

Meiyerditch
Take the boat from Burgh de Rott and get caught by a Vyrewatch. Choose to do hard labor and get sent to the mines. Ask a miner for a spare pickaxe, mine 15 daeyalt ore, deposit them in the mine cart, and then talk to one of the guards to be let out. Then run south along the eastern wall. The spot is in an indent in the wall (on the minimap), right next to a sitting child. Dig where it bwuks four times just like in the quest. The coordinates for this location are 3 degrees, 41 minutes north 37 degrees, 31 minutes east. Alternatively, use Drakan's medallion to teleport to Meiyerditch, then make the quick trek northwards.

Attracted items
The alerter works with:
 * Blisterwood stakes
 * Bow arrows
 * Crossbow bolts (Includes royal bolts, bone bolts, kebbit bolts, and broad-tipped bolts. It will not work with black bolts.)
 * Darts
 * Javelins
 * Throwing axes
 * Throwing knives
 * Toktz-xil-ul

Other items that the alerter can occasionally attract and deposit in the inventory include:
 * Iron ore
 * Steel arrows (most common)
 * Steel bolts (second most common)
 * Steel darts
 * Steel knives
 * Steel helms
 * Steel nails
 * Toy mouse

Trivia

 * The examine text is a pun on the U.S. police motto "Ready to Serve and Protect"
 * The Alerter attracts Toktz-xil-ul and Blisterwood stakes even though they are not metal.