How to "dominate" enemy heroes

On one of the pub games i had where Aiushtha (Enchantress) was on my team, we had this one mid-game clash where enemy Pudge's hp turned green and became invulnerable, clearly suggesting he got dominated (like that helm-of-dominator type of domination), no, my mind tricked me not, that's for sure. Well off course Echantress has this amazing eponymous skill (where she could dominate even illus, if my mem'ry serves me right), but the description strictly says that if the target is a hero, it would slow the target instead. Is this some sort of bug or am I missing something?