This contents are summarized from our experiences, thus they are not 100% right, but they are working.
1. Type of Caves
There are 5 types of cave
1. Normal Cave, gives low rank eggs
2. Silver Cave, this cave only appear when you are taking certain villager request. The eggs are vary from low rank to normal-quality egg.
3. Gold (rare) Cave, the eggs are vary from normal to high-quality egg
4. Fixed Species Monster Cave, gives a specific egg (not random, but fix)
5. Red Cave (Hirank), gives hirank monster egg
2. How to find Fixed Species Monster Cave
Fixed species monster cave only appear whenever you beat monster then they run away after battle.
This type of cave gives you nest mark on your map, and it has different cave title (e.g. Rathian cave, etc).
Based on our experience, you have to clear the story in that area to let monster run away after battle.
If you haven't clear the story in that area, you only killing them, they won't run away after battle.
Note: we are not 100% certain about this, but it happens to us.
3. How to increase monster-running-away rate?
Use Paint Ball 3 turns before the monster die, it will increase running-away rate after battle.
It applies on random monster that you found in open map and/or monster that summoned by Qurupeco.
Using Rathian armor (or other armor that has 巣守り-Nest Guardian skill) will increase running-away rate.
It certains that some monsters have extra condition to increase their running-away rate.
(Please refer to our Monster List
for monster details)
Please note that not all area/map are nest-able, it means monster can't run away to their nest on certain areas.
4. Easy way to find monster
Put Qurupeco in your party, and use him to summon monster. But it require RNG to find a rare monster.
If you have been summoning for a quite long time and your desire monster hasn't summoned yet,
Try to go back to camp then move to another city, sleep, then go back to summoning area.
It will refresh your RNG.
Another way, take certain side quest that require you to kill rare/uncommon monster,
Since it gives 100% spawn and give you the location on your map.