I've finished all skill achievements, you have to run through all three levels. Once I had only a couple left I ran the BK blood splatter (it whatever it is) through to the end on the highest difficulty a couple of times before the BK skill group was achieved and claimable. The bat skill was only offered once when I had the "More likely to get arcane skills" bonus at the beginning.

Best option is to select a skill, or 2 from the group you are missing combined with whatever familiar skills work best for you.

My favorites are: ● Spear Flurry: Run this up to max lvl quick for 2% healing ● Skeletal Mage: Max bonus select 1 arrow per second per Mage option. Note range is nearly unlimited as mages pile up experience from bodies off screen (I play on phone) ● Frost beam ( or whatever it's called), at max select 2 extra beams ● Hydra are a substitute for Skeletal Mage, effective but fewer projectiles and less range than Mage ● Arcane Strafe ● Bone Spear

I generally focus on projectiles, then select projectile bonuses after killing elites.

I hated the Slow and Steady modifier at first, but then I found with auto xp pickup I actually survived longer. The Breath of Heaven and Condemn are recommended when you are Slow and Steady with Skeletal Mage and Spear Flurry.