On zombies and vampires cast cure or use a potion on them... I don't get why you have to be an illusionist.

Wygars are obtained first when you either steal it off someone (usually a fighter or a gladiator) or a skill level up special item gift or if you do a special sort of country / treasure hunt organisation you will get it- there are probably many other ways. Now Sky will probably jump in soon and explain it to you in further detail.

PS: You can get wygars from a clan battle but the odds of getting it is low.