More Keyword effects, that may be added to the release or future ones

I have been thinking of more keyword effects that will help players strategize. I will write these and include design notes to ascertain why they would make good game mechanics, the possible pros, cons and uses of these; also there will be examples of what might go on a card, giving you a little sneak preview into what could come next!

"[Support: X]:"
(If the card played on top of this one is describable by X, they get the following effect.
This effect happens after the card's own abilities. For example, if a card that needs to be POW 4 becomes POW 5, it wouldn't be able to gain the "Support Effect.")

Examples:

• [Support: POW 4 or less]: That card gains +1POW
• [Support: Block]: That card cannot block, it gains +2POW

Design notes:

• These cards will require quite specific cards to be activated; this rewards players for having a deck centeralized around an idea.
• These cards could also be used to bluff your opponent, or increase the playability of your hand.

"[Fill: X]"
(If there are X cards of the same colour as this card in your pile, this card gains the effect.)

Examples:

• [Fill 4]: You gain 3 Life
• [Fill 2]: Deal 1 Damage to your opponent
• [Fill X]: Discard a card, Search your deck for a card with POW X or less and put it into your hand
• [Fill X]: Shuffle X cards into your deck from your graveyard.

Design notes:

• A future expansion will be more geared to helping decks with fewer colours in them, these cards will reward players for fitting into this.
• There will be a multitiude of effects that can be played this way.
• There will be checks for "Fill" cards.