So, after leveling a Frost Mite to 5 slots and putting Rune Corruption on him, i can confirm that picking Rune Corruption first will prevent them from picking any additional Special Moves. Ruined a decent Frost Mite that way, at least i didn't put any Power Scrolls on him yet.
So i went onto TC, tamed a 2 Slot Frost Mite, trained his skills to GM and leveled him up twice. I was able to put Armor Ignore on him first, then put Rune Corruption on him as well. Make sure Rune Corruption is the last of the abilites that you add.
Also, when a 2 Slot Frost Mite is trained up to GM skills (Wrest/Tact/Resist/Anat/Parry/Med/Focus), it'll cause him to jump an additional slot when leveled, so he'll go from 2 Slots to 4 in a single Level Training Session. So there's no point going after 2 Slot Frost Mites, just go for a nice 3 Slot Frost Mite with high Health so you can save some Training Points.
So i went onto TC, tamed a 2 Slot Frost Mite, trained his skills to GM and leveled him up twice. I was able to put Armor Ignore on him first, then put Rune Corruption on him as well. Make sure Rune Corruption is the last of the abilites that you add.
Also, when a 2 Slot Frost Mite is trained up to GM skills (Wrest/Tact/Resist/Anat/Parry/Med/Focus), it'll cause him to jump an additional slot when leveled, so he'll go from 2 Slots to 4 in a single Level Training Session. So there's no point going after 2 Slot Frost Mites, just go for a nice 3 Slot Frost Mite with high Health so you can save some Training Points.