So I'm just going crazy trying to understand what stacks and doesn't I'm running a druid bear tank right that is a dwarf so I maxed out con strength came second as dwarves get throw you weight around changing damage mod to con for dwarven axes and only using strength for attack mod IV taken improved critical slashing and overwhelming critical I also for enchantments focused Natures Protector for capstone and tier 5s but I had 21 points left which was just enough to get too the 4th core of Natures Warrior for a 1 to critical multipliers so when using a dwarven axe I should be at least (10%/ 19-20 x5) but I'm still at (5%/ 20 x4 so does Natures Warrior not stack with overwhelming crit and why is my crit roll only at a 5% d20 I have improved crit to increase critical threat range so should at least be 10% d19-20 and what critical multipliers stack or dont stack?

Just want to get the most out of what I can without wasting enchantments or feats on a side note I am lvl 21 rn when I hit cap at 30 and can take legendary dreadnoughts tier 5 for 1 crit multi on a 19-20 roll for slashing weapons will this stack with everything else or maybe I am getting the correct crit profile and its just bugged to not show everything that's stacking depending on how the devs incorporated it in any answers would be much appreciated!!!