Rathis is the corbicula rex matriarch, one of the four Rex Matriarchs. Rathis attacks with poisonous ranged attacks and is weak to melee, specifically stabbing weapons. Although she counts as a dinosaur for the purpose of a Slayer assignment, Tuska's Wrath will not deal its full damage.
Rathis along with the other two matriarchs are experiments from the DactyldragonkinKerapac, who surgically removed glands and sacs from Raksha and grafted them to the matriarchs; specifically, venom sacs that allowed Raksha to poison foes through spitting it and through spines on its body were grafted into Rathis. Kerapac considered the surgery a success, despite the lowered potency of the ability the matriarch displayed compared to how Raksha was able to use it.
At some point, Kerapac used either the eggs of the matriarchs or the offspring of their eggs in experiments to combine the traits of the other matriarchs along with dragonkin blood. These experiments eventually led to the creation of the egg that would hatch into the Queen Black Dragon, with another dragonkin, Phalaks attempting something similar; his experiment led to the creation of the King Black Dragon. Kerapac's experiment kept many of the qualities related to size and power of the dinosaurs, while Phalak's experiment kept the original attributes obtained from splicing Raksha's glands.
There is a 1/128 chance of rolling the rare drop table. Luck-enhancing items are not required to access the table, but they will increase the chance of accessing the rare drop table and may also improve the loot received from it.
^ abcdTo receive pieces of Skeka's hypnowand, the Aged journal must have been read previously. There is a 1/500 chance to roll for a hypnowand piece; however, there is a 70% chance that this will be a focus piece and a 10% chance for each of the other three pieces, respectively. Luck increases this drop rate: tier 2 multiplies it by 100/99, tier 3 by 100/98, and tier 4 by 100/97.
^Pristine Corbicula rex egg has a base drop rate of 1/2,000 with a threshold of 1,000.
Feeling a Little Venomous Today ( 10, 2) – Defeat Rathis solo after stopping her from healing during her 'Poison absorption' attack.
Extinction Event ( 15, 3) – Defeat the Rex Matriarchs, Pthentraken, Orikalka, and Rathis, all within 5 seconds of each other. Can only be completed in a solo instance.
The 50% combat experience reduction on bosses has been removed. Bosses now give 50 combat experience per 1,000 life points, like most other monsters in the game.
This week the Rex Matriarchs come roaring into the game with a new combat challenge for experienced fighters.
You'll go up against three respawning bosses. Each has a different strength to test your mettle, but also a different weakness to be exploited. Grind those kills and earn powerful rewards to boost your Combat playstyle, or maybe even get your hands on the iconic Laniakea's Spear - T90 damage / T75 accuracy is not to be sniffed at, plus, it'll give you 5% extra poison damage and +5% chance to apply poison when used. Veteran RuneScapers may recall classics such as Dagannoth Kings while new challengers will enjoy a brutal test of their combat mastery. Note that access to Anachronia is required to take on this challenge. So what are you waiting for? Grab your best gear and head to central Anachronia. The lair of the Rex Matriarchs awaits...
^Jagex. Mod Orion's Twitter account. 23 April 2021. (Archived from the original on 24 May 2021.) Mod Orion: "Rex Matriarch pet drop rates: 1/2000 with a 1000kc threshold."