G.28.1- A spell or ability may instruct you to put a card into play. This is not considered to be "playing" or "casting" that card for any reason. You do not pay any costs which are paid when playing the card. [D'Angelo 1998/02/03]
G.28.2- When putting a card into play, any X in the mana cost of the card is zero. [D'Angelo 1997/12/29]
G.28.3- When putting a card into play which has undefined characteristics,
you must do what is required to define them. For example, a Clone
requires a target creature to copy, and Minion of the Wastes requires
a payment of life. You take these defining actions during the resolution
of the spell or ability which is putting the card into play. This kind
of action is usually denoted on the card by the text "As this card comes
into play, do
G.28.4- If a card requires a target when played, and that card is put into play without playing it, then you must choose a target at the time it is put into play. [Aahz 1997/02/16] If there is no legal target, then the card stays where it is and does not get put into play. [bethmo 1998/05/02]
G.28.5- If a local enchantment is being put into play without playing it from your hand, the player putting it into play chooses a permanent for it to enchant right before it enters play. If there is no legal permanent for it to enchant, it remains in the zone it was in. [CompRules 1999/11/01]