summon

Yes, a facedown monster can be Tributed in order to Tribute Summon a monster. But as usual, you can only Tribute Summon if you have not already done your "Normal Summon or Set" for the turn. To perform the Tribute Summon, during your Main Phase I or II, send the monster(s) you are Tributing to...

You cannot perform a Flip Summon during your opponent's turn. A Flip Summon is a way of manually changing the monster's Battle Position. Since it is "manual", it can only be done during your own Main Phase. You cannot use Ultimate Offering to Flip Summon a monster during your opponent's turn...

When performing a Special Summon, you do not need to Tribute monsters as you normally would for a Tribute Summon. However, you have to fulfill the requirements to make the Special Summon. For example, Megarock Dragon requires that Rock monsters be removed from the Graveyard first. If a card...

The general rule is that you can only "Normal Summon or Set 1 monster per turn". Usually when people "play a monster", this is what they mean. Tribute Summons count as Normal Summons, so you cannot Normal Summon a monster and Tribute Summon in the same turn. Special Summons can be done as often...

A Special Summon can only take place when a card effect allows you to. Normally the card effect will specify a place that the monster being Special Summoned will come from. For example, "Special Summon from your Graveyard". If it is not specified, usually you can only Special Summon it from...