Celestial Dawn makes all lands you control into Plains, so that they have "T: Add W" and lose all their other usual abilities (C.R. 305.6, 305.7). This is the case regardless of what those lands otherwise are (whether Swamps, Plains, or otherwise). Moreover, Celestial Dawn doesn't change the names of any of those lands. Moreover, even though the mana is white, you can also spend that mana as though it were mana of any color, thanks to Celestial Dawn. (It doesn't mean you can tap Plains for any color of mana or that you can tap other lands for colorless mana only — compare Celestial Dawn with Pulse of Llanowar or Pale Moon.)
Note that while you can spend white mana as mana of any color, you are still spending white mana. That is, if you were to use it to cast Engineered Explosives, you get 1 counter (since you only spent white mana) or you cast Painful Truths, you get 1 card and lose 1 life since you only spent white mana.
okay so then all lands can tap for whatever mana basically
Again, Celestial Dawn's last ability doesn't mean you can tap Plains (which all "[l]ands you control" become) for any color of mana; however, the effect is that you can cast, say, a spell costing B by tapping a Plains for W and spending that W as though it were B to pay for that spell.
I don't really see any clarified ruling of Celestial Dawn anywhere... some people say it doesn't work, but the words on the card seem to imply this:
If I have a white and black deck (half plains, half swamp) then if I play this card, ALL of my names of my lands will turn into "plains" lands....
That's great and all.. that means if an opponent has "plainswalking" then that would be unblockable because all my lands are plains...
..but if I tap my swamps it doesn't count as white mana, it counts as COLORLESS mana....
..and if I tap my plains, it counts as ANY COLOR mana!!!
real swamps = colorless mana
real plains = any color mana
I believe this is what the card says... am I correct?
Or can ALL of my lands now tap for ANY COLOR mana, regardless of whether they are swamps, forests, or whatever...??
as in
any land = any color mana
Celestial Dawn makes all lands you control into Plains, so that they have "T: Add W" and lose all their other usual abilities (C.R. 305.6, 305.7). This is the case regardless of what those lands otherwise are (whether Swamps, Plains, or otherwise). Moreover, Celestial Dawn doesn't change the names of any of those lands. Moreover, even though the mana is white, you can also spend that mana as though it were mana of any color, thanks to Celestial Dawn. (It doesn't mean you can tap Plains for any color of mana or that you can tap other lands for colorless mana only — compare Celestial Dawn with Pulse of Llanowar or Pale Moon.)