I'll keep this suggestion short because it is the most problematic part of mining in my opinion.
As a person who did a SUBSTANTIAL amount of solo mining on layer 9 nothing is more annoying than having back to back to back max size slime packs spawns while digging a tunnel. When it happens, it is a necessity to run back and fight them (Unless you are a fucking titan and can facetank 12 slimes at once).
Running back to the opportune spot or just till you lose aggro, and then clearing them out, makes a person lose valuable time.
Now count that per trip ( I measure a trip until I spend 5000 energy), you can spawn anywhere from 2 to 6 packs of slimes or boreworms.
That is a lot of time being wasted, on top of mining already being very resource and time demanding.
Having multiple fights like these would make you wounded and weaker, generally ruining other potential trips down because you do not want to risk any more incidents.
What am I suggesting is to add an ability to sense danger in the tiles ahead. Something along the lines of last reward for finishing miner credo "Ability to sense ore ahead".
The ability would be acquired by finishing the cave hermit credo.
When mining a tile that has a slime seed or boreworm seed in it, it would say : "Something creeps in the stone" or "Something tremors in the stone". Area affected would be 3 by 3 ( same as ore sensing ability).
Yes, having this option to sense danger ahead would completely nullify the danger in mining, but that advantage could be lessened by :
1.Having a XP cost to activate similar to "mine song".
2.Having a cool-down between finding danger nodes.
Example : If I find a danger node, the game will alert me with a message if it try to mine dangerous tiles that belong to that node but it wont alert me to new danger nodes one in a period of 1 minute or so. A person could potentially still find a different danger node and just spawn a pack if they decided to mine a little bit away.
3. Slightly higher chance of danger nodes being in the ores compared to regular stone.
This would promote team-play in a positive way, instead of your townie just afk sitting waiting for something to happen.
The only problem I see about my suggestion is regarding the actual code, whether the monster packs are seeded in the tiles or procced on a %.
Hope you guys like it.