These are the limits of magic, what can be done and what can't be done now that the Black Phoenix is emitting the power of anti-magic.

What you can't do

• All magic by use of wands is impossible. Occasionally a echo will occur and a wand may send out a spark of magic but apart from that a wand is useless.
  
• Random bursts of non wand magic are rare. Most of the time, wizards are as powerful as muggles and so their magical capabilities cannot be used. Though as with wand magic. Sometimes someone may burst out with magic if there is a glint in the 'signal'
  Most people are prosecuted if this does happen.
  
• Some potions, more the complex potions do not work.
  
• Magical defences around buildings have failed. Thus the ruins of Diagon Alley are fully visible to muggles, Hogwarts, though high in the highlands of Scotland, are visible, the ministry of magic, though underground has lost much of it's magical essence.

What you can do

• Some minor potions, i.e. poison antidotes are able to be used as they are mere concutions of different substances rather than magic itself.
  
• Magical animals still retain they're magical abilities, House Elves included. They are, thus shunned by the new order and many have been killed.