2015-08-25
Once you legally activate the ability, it doesn't matter what happens to the other colorless creature. The ability will resolve and create a regeneration shield even if you don't control another colorless creature at that time.

2015-08-25
Skitterskin's activated ability doesn't depend on Skitterskin being colorless. If it gains one or more colors, you can still activate the ability if you control another creature that's colorless.

2015-08-25
Cards with devoid use frames that are variations of the transparent frame traditionally used for Eldrazi. The top part of the card features some color over a background based on the texture of the hedrons that once imprisoned the Eldrazi. This coloration is intended to aid deckbuilding and game play.

2015-08-25
A card with devoid is just colorless. It's not colorless and the colors of mana in its mana cost.

2015-08-25
Other cards and abilities can give a card with devoid color. If that happens, it's just the new color, not that color and colorless.

2015-08-25
Devoid works in all zones, not just on the battlefield.

2015-08-25
If a card loses devoid, it will still be colorless. This is because effects that change an object's color (like the one created by devoid) are considered before the object loses devoid.