magic players i call upon thee again

i recintly posted a deck list in deck ideas called ''awakening of the Wurms'' and the cost of this deck is a bit much, i'm mainly wanting flash and layline of anticipation, but will trade for any on the list, thanks.

what is the rolle of the commander in EDH?

You start with him in a special zone, and can play him as if he was in your hand. Whenever he dies, he goes back to the zone and you can play him again, but it costs 2 more mana to do so for each time he's gone back there.

ok thanks.
are there any constraints on what the card is?

It has to be a legendary creature.

And your deck can only use colours that are in the casting cost of your Commander.

Ok thanks
Mine will be a 5-color deck ....which may be turn out to be prohibitively slow.
I guess its an advantage then to use a CMC=5.
Most legends dont come in much under this anyway....

Most Commander decks are painfully slow

In Commander you start with extra life too, so its not much of an issue.