­Boon of Emrakul
­Red or green creatures will get +3 power, but if they're toughness is greater than four, it may go down to four, but not below four.
­White or blue creatures will have their toughness reduced to 0 and die.

­Watchwolf- Yeah, this card breaks in conflict with itself.

How do these interact with Boon of Emrakul?

How do these interact with Watchwolf?

I like the alternate timeline concept. The flavor text communicates the idea in a pretty sloppy way.

On further reflection, I just remembered that even improving the card like that we end up with a less versatile Concerted Effort that requires more creatures to work and synergizes with only two rather than eight keywords.

I feel I already commented on a card very similar to this. A card that does nothing until you have your fourth creature is already quite hampered, but this one also requires you to play some sort of keyword tribal... except getting the keyword counter itself is not useful if you actually go all-in on the keyword.

You have to arrange not only for your fourth creature, but for the other three creatures all to belong to subset A of your creatures, but this fourth one doesn't belong to subset A. That is not the "interesting decision making"-kind of tension, that's "the card doesn't get to be useful a lot of times because the stars didn't align"-kind of tension.

Now all that said, I also look at the reward you get here, and while entering with counters and having a static ability granting keywords are different, they are similar enough (and have pros and cons balancing each other out) that the following question might be appropriate: Wouldn't be about an appropriate cost for "All creatures you control have vigilance and menace"? Does the pay-off this provides really need hoops?

At the very least... would it be so bad if you just outright removed every mention 0f color from this card's rules text?

On a more technical note: static abilities and timestamps and dependency might be confusing on this effect that grants the keyword the condition is looking for... Would this be better as a triggered ability?

Compare:

• "At the beginning of combat on each turn, if you control three or more creatures with vigilance, creatures you control gain vigilance until end of turn."

It feels weird to have this set of abilities for a creature half that is prevented both from attacking and blocking by the mechanic.

If the creature was applied for the untapped state you could at least block with it, maybe use vigilance to attack with it.

That aside this particular design doesn't go quite far enough in making the 'decision to tap' interesting enough. There is not zero synergy between the halves. In a weird way though the synergy lies in the creature-half undoing the life loss inflicted by the artifact half i. e. the card becomes less appropriate for black.

Maybe it would be more interesting and create a modicum of tension and decision-making to trigger on upkeep rather than end step? That way not waiting until the last moment with the artifact activation is rewarded in a similar way addendum works.

See Vapor Fate Vial // Caligomancer.

Name misspelled

This exists in an alternate timeframe when Karn actually perished at the hands of Elesh Norn but his heart was able to be salvaged.

If a 2/2 white Knight creature token has four +1/+1 counters on it, the creature exists as having base power of -5/-5. If a +1/+1 counter is removed, the creature's power and toughness will automatically recalculate to 1/1 without the creature dying. However, a single -1/-1 counter will kill the Knight.

­Llanowar Elves is a 4/4, Llanowar Elves with two -1/-1 counters is a 4/4, with a base power and toughness of 6/6. If any number of -1/-1 counters (or other -X/-X effects) affect that Llanowar Elves, its base power and toughness automatically recalculate to maintain a power and toughness of at least 4/4.