Focus is an active ability.
2 (other): When the target creature attacks this turn, its attack cannot miss.
So it's like an active skill of Momentum only without the +1|+1
Yes. However, it can also be used on another, non-immaterial creature. The other difference is that it only lasts one turn.
That leaves me with a conundrum. I can either leave things as they are and hope that the cards aren't too UP, or I can change the effect of the ability Focus.
I think the benefit of this card is that it can reduce the need for multiple Momentum/Unstoppable in Rainbow decks. The downside is that it is ineffecient in its use of quanta. I'm not as experienced as some, so I would appreciate your thoughts as to whether the benefit outweighs the downside.