It's fairly easy to create a custom shaped Oasis with MicroVerse. One important thing to note though: If you have a custom spline area, then the transform of the height stamp must match. I've added a convenience function to Genesis's Terraform Module with which you can achieve that at the click of a button, see at 00:32.
00:00 Start with desert map
00:02 Create oasis spline
00:10 Auto tangent on all knots for smoothness
00:14 Spline as spline area
00:20 Height stamp set to override to carve terrain
00:30 Showing alignment necessity
00:32 Align automatically
00:36 Shape lake
00:48 Add and position water
01:02 Add oasis biome at full range
01:06 Shape oasis biome with spline
01:20 Clear stamp to remove all vegetation from water
01:30 Boost spline area on the vegetation
The part with clearing / boosting can be achieved in different ways, but I guess you get the point 😉
Assets used:
[⭐ Summer Sale, 3rd Week ⭐] Ultimate StampIT! Collection
https://assetstore.unity.com/packages...
[⭐ New Release Sale ⭐] Sand Covered Desert Rocks
https://assetstore.unity.com/packages...
(note: included in the Ultimate StampIT! Collection)
[⭐ Summer Sale, 3rd Week ⭐] MicroVerse - Core Collection
https://assetstore.unity.com/packages...
URP 3D Sample
https://discussions.unity.com/t/intro...
(use Unity Hub for installation)
Genesis for MicroVerse
https://assetstore.unity.com/packages...
Biomes and Presets 2 for MicroVerse
https://assetstore.unity.com/packages...
SceneNav - Smooth & Fast Scene Navigation
https://assetstore.unity.com/packages...