Zephrys needs to be "helped" in order to influence his choices.
An example for this: Tonight I had an even shaman as opponent, who had 3 or 4 minions with 2 HP on the board and played a Flamewreathed Faceless (7/7 Stats). On my side was a 5/5, I had 6 Mana and Zephrys in my hand. Following considerations:
a) Playing Zephrys now would have offered me a SW:Death for the 7/7, but all other minions would stay. b) I decided to trade my 5/5 into the 7/7, which now had 2 HP left. Then I played Zephyrs, because I wanted a Consecration. -> I got it and could clerar the enemy board fully.
So think about 1) what you want to get and 2) how you get it -> how you have to manage your board and mana to get Zephrys giving you exactly the card you wish.
An example for this: Tonight I had an even shaman as opponent, who had 3 or 4 minions with 2 HP on the board and played a Flamewreathed Faceless (7/7 Stats). On my side was a 5/5, I had 6 Mana and Zephrys in my hand. Following considerations:
a) Playing Zephrys now would have offered me a SW:Death for the 7/7, but all other minions would stay.
b) I decided to trade my 5/5 into the 7/7, which now had 2 HP left. Then I played Zephyrs, because I wanted a Consecration. -> I got it and could clerar the enemy board fully.
So think about
1) what you want to get and
2) how you get it -> how you have to manage your board and mana to get Zephrys giving you exactly the card you wish.
I would have managed to have 4 mana left when playing Zephrys (play Bog Slosher before). Then you have a huge chance for a (4) Hex.