If I control a Celestial Dawn , would "comes into play tapped" lands, such as Sejiri Refuge , come into play tapped? And would I gain the 1 life? Thanks in advance
"Enters the battlefield tapped" is a replacement effect, changing how the permanent enters play, at that moment, it's not yet subject to copy/change type effects, it enters tapped. The "gain life" part is a triggered ability. As soon as the land entered play, it is a plains right away, the game checks for any trigger that should trigger, it sees none on your plains. Game goes on...
Rules question? Have you read the Basic rulebook already? No? Why not take some time to do that?
How to autocard (do this to specify a card in your posts): Type [c]Black Lotus[/c] to get Black Lotus . Type [c=Black Lotus]The Overpowered One[/c] to get The Overpowered One .