Ephraim's Mechanic Gone Wild Part Trois

[Godder]

I've picked Blue and White, since Blue often taps creatures, and White often untaps creatures, leading to the following card:

<Cardname>
W/U W/U
Instant
If was spent to play <cardname>, tap all creatures.
If was spent to play <cardname>, untap all creatures.

Current Wording:

<Cardname>
W/U W/U
Instant
If was spent to play <cardname>, tap all creatures.
If was spent to play <cardname>, untap all creatures you control.

I'm unsure of mana cost, but 3 seems about right for the Blue card, while the White ability seems to be worth about W, so I've costed it at CMC 3.

Edit: Casting cost increased to CMC 4.

[Matt]

Yeah the blue one is much stronger than white.

I kind of liked it when the white part undid the blue.

[Anusien]

I'd compare this to Turnabout, and put it at 2 W/U W/U.  I like it though.

[Godder]

Turnabout is amazing because it's so versatile, but CMC 4 is still 'fair' and the card is admittedly very good in Limited.

[Godder]

While a name and flavour text is needed, the card itself hasn't provoked any serious complaints. 24 hour clock.