Yet Another Phyrexian Dreadnought Question

[Anusien]

If you have Gamekeeper in play as your only creature in play, and you cast Phyrexian Dreadnouth, what happens?  Are you forced/given the option to sacrifice the Gamekeeper, even though you don't have 12 points of power on the table?

[Mykeatog]

Yep.

[Nibble]

You're forced to sacrifice him. This confused me a lot until it was properly explained to me, but the reasoning is that you always do as much as you can, even if you know you can't complete the full action. If an effect tells you to discard three cards and you only have one, you discard as much as you can. If Dreadnought tells you to sacrifice creatures with a total power of 12, you sacrifice creatures until you reach 12 power or you have no more creatures.

[spawn]

this is wrong!

Ive been told by a judge that as long as you cant sacrifice 12 in power, you dont need to sacrifice anything.

so this whole wrath of god thing is false.

/spawn

[Jebus]

this is wrong!

Ive been told by a judge that as long as you cant sacrifice 12 in power, you dont need to sacrifice anything.

so this whole wrath of god thing is false.

/spawn

Your judge was wrong.

Mykeatog and Nibble are correct.