Rulings
Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keywords are activated abilities and will have colons in their reminder text.
(wotc • 2016-06-08)
The extra mana is not considered part of the activation cost. It is a separate cost.
(wotc • 2004-10-04)
The extra mana is part of the total cost, so cost reducers can be applied to this cost.
(wotc • 2004-10-04)
The additional mana is paid at the same time the spell/ability is cast/activated.
(wotc • 2004-10-04)
Rulings
Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keywords are activated abilities and will have colons in their reminder text.
(wotc • 2016-06-08)
The extra mana is not considered part of the activation cost. It is a separate cost.
(wotc • 2004-10-04)
The extra mana is part of the total cost, so cost reducers can be applied to this cost.
(wotc • 2004-10-04)
The additional mana is paid at the same time the spell/ability is cast/activated.
(wotc • 2004-10-04)