2015-08-25 : A landfall ability triggers whenever a land enters the battlefield under your control for any reason. It triggers whenever you play a land, as well as whenever a spell or ability puts a land onto the battlefield under your control.

2015-08-25 : If the ability has an additional or replacement effect that depends on the land having a certain basic land type, the ability will check that land’s type as the ability resolves. If, at that time, the land that entered the battlefield is no longer on the battlefield, use its types when it left the battlefield to determine what happens.

2015-08-25 : If, during its controller’s declare attackers step, Akoum Firebird is tapped or is affected by a spell or ability that says it can’t attack, then it doesn’t attack. If there’s a cost associated with having it attack, its controller isn’t forced to pay that cost. If they don’t, Akoum Firebird doesn’t have to attack.

2015-08-25 : Players can respond to the triggered ability, but once it starts resolving and you decide whether to pay {4}{R}{R}, it’s too late for anyone to respond.

2015-08-25 : The landfall ability triggers only if Akoum Firebird is in your graveyard at the moment the land enters the battlefield.

2015-08-25 : When a land enters the battlefield under your control, each landfall ability of the permanents you control will trigger. You can put them on the stack in any order. The last ability you put on the stack will be the first one to resolve.