Can some one explain?

Thanks

DROWN WAKANDA: All squares at Namor's level of elevation or lower; in rows from the edge of the map that your starting area is closest to, through the row Namor occupies, are water terrain, in addition to any other terrain.

EDIT: Damage Power

As Namor moves across the map, all squares starting with his Starting Area to where ever he is now, are Water Terrain IF he is at, or above that elevation.

Namor in his starting area at elevation 3. Since he's not yet moved, only that back row is water
333N3333
33333333
22222222
22222222
11111111

Namor moves to Elevation 1. Now, all Elevation 1 squares are water terrain (in addition to any other terrain type.)

33333333
33333333
22222222
22222222
111N1111

Namor in his starting area at elevation 1. Since he's not yet moved, only that back row is water
111N1111
11111111
22222222
22222222
33333333
33333333

Namor moves to Elevation 3. Now, all Elevation 3 AND LOWER squares are water terrain (in addition to any other terrain type.)

11111111
11111111
22222222
22222222
33333333
333N3333

Ok, I get it now thanks

So, using

"SIEGE COURAGEOUS: Once per game, give Namor a double power action. Place him and any other friendly characters with the Phoenix Force keyword anywhere on the map, then end your turn. "

Namor could move from one end of the map to the other and, depending on his elevation, theoretically turn the whole map in to water by moving him from end of the map to the other.

Splash!

Oh, but keep in mind that if Namor moves back toward his starting area, the water moves with him.

Haha I like the way you think