Tips For Monster Slayer Goal

Guide

Preperation

To get the monster slayer goal I'd recommend to prepare so you don't die
(unless you're speed running).
You would most likely need a tier 9 weapon (or tier 6 if you're good with combat)
level 120 mines is also required so make sure you do that first
stockpiling on monster musk is useful too.

Execution

Once you have everything prepared one thing you can do is find an infested layer in the mines or skull mines.
If you find one then you can use your monster musk and keep reloading it.
If your in the skull mines this is much more challenging to pull of unless you have ladders.
After that just farm till you get the goal, it may take awhile but its an easy way without cheats.

Tips

1.)For slimes it may be easier to have a slime hutch and the slime ring.

2.)Try and get the dust sprite goal quickly so you get good loot while farming enemy's with the burglars ring.
3.)Bring a lot of food for the shadow people (they hit hard).

4.) Don't do this in the dangerous mines.