Okay, quick question: If someone chose to make elevated terrain clear terrain with Skrull Dum Dum Dugan's special power, would hindering, water or blocking terrain that is on hindering terrain become clear terrain? Basically, can terrain be considered more than one type of terrain? Would hindering, water or hindering terrain that is on elevated terrain also be considered elevated terrain? As always, thanks in advance.

S.W.O.R.D. FALL: Before the beginning of the first round, choose one area of elevated terrain or blocking terrain on the map. This area is considered to be clear terrain until the end of the game.

Indeed.

Various types of terrain (Outdoor/indoor, elevated/grounded) are merely modifiers. It is entirely possible, say, to have indoor, elevated, hindering terrain.

That said, specifically regarding SWORD Fall, the player's guide has this to say:

The last sentence of S.W.O.R.D.fall reads: “This area is considered to be clear grounded terrain until the end of the game.”

The selected area from S.W.O.R.D.fall does not remain clear grounded terrain regardless of other game conditions. Terrain markers, objects, etc. would all behave as hindering/blocking terrain as normal.

So, if there was water terrain on the elevated terrain, the first clarification would eliminate both the hindering and elevated part, leaving plain old clear grounded terrain.

But, later on, you could have Tempest come strolling through later on in the game, making the area water terrain again, per the second clarification.

Scenario Fing Fang Foom could potentially make all kinds of new terrain in the SWORD Fall area, too.

Thanks but I'm still not entirely getting it. So let's say the map looks like this:

CCCCCCCCCC
CCCCCCCCCC
EEEEEEEEEEE
EEHEEEEBEEE
EEEEEEEEEEE

C = Clear, non-elevated terrain
E = Elevated
H = Hindering
B = Blocking

Dugan chooses to make that area of elevated terrain into clear terrain. Would the map now look like this:

CCCCCCCCCC
CCCCCCCCCC
CCCCCCCCCC
CCCCCCCCCC
CCCCCCCCCC

or this:

CCCCCCCCCC
CCCCCCCCCC
CCCCCCCCCC
CCHCCCBCCC
CCCCCCCCCC

Thanks again.

Again, from the player's guide:

The last sentence of S.W.O.R.D.fall reads: “This area is considered to be clear grounded terrain until the end of the game.”

Hindering and blocking terrain are not clear terrain. Your first diagram is correct.

Okay so if there's hindering/water/blocking terrain on the elevated terrain, it becomes clear too. Thank you.