a hump like a snow hill achievement

[Na]

Is there any trick to this
does it spawn it a specific system?

[Kythe]

If you are specifically achievement hunting this, I would recommend the following. If not, just play the game and you will find it eventually. (therefore spoilers)
First, a very good Stellaris youtuber names aspec, does videos on all leviathans and such, but they may be slightly outdated.
Link here:
https://www.youtube.com/watch?v=32J6mPnjQQQ
As a summary, it seems the matriarch spawns in a system with a single Gaia planet. (see end about such system) It has mostly (all it seems) armor so armor busing weapons would be more effective. (ex. Lasers or plasma) anti hull may help too. (ex. mining lasers or launchers) It seems that evasive corvettes and destroyers help due to it inly having two weapons. It is also recommended to use more shields as though its main weapon does more damage towards both armor and shields; its secondary weapon does less damage to shields.

Grabbed this but it might be outdated
hull = 137250
shield = 0
armor = 15921
secondary weapon = 250-1000 damage every 2.7 days; -75% shield damage; +100% armor penetration

primary weapon = 4948-12123 damage every 21.75 days; +100% shield damage; +100% armor damage

lastly remember that this leviathan is for distant stars only, meaning that it is most likely located at the end of an L-Gate system, though I may be mistaken.

Happy hunting.

[mcsproot]

Like all Leviathans the Tiyanki Matriarch randomly spawns (or doesn't) if you have the Distant Stars DLC installed. Larger maps have a higher chance of having it spawn.

Then you simply kill it. The above poster already listed a guide, but the standard '20k of fleet power and bribe the Curators for bonus damage' generally works.

[Olinser]

The easiest way to get any of the Leviathan killing achievements is to play 1 game on largest size map as they have significantly more spawns so its much more likely you'll find the one you want.

Small-medium maps only have a handful of Leviathans in them.