But less efficient in card slots. If you want to use multiple of these, you want to use less activators for them; it's why, say, SoW Reflect uses 2 nymphs 4 quint instead of 6 quint; 1 nymph does all the quinting you'll need. Card slots are a lot more precious in ETG then other games.
If you're only using 1-2 of these souls, you're going to have to justify putting in the 3-4, say, momentums needed to reliably have the momentums and souls connect; and you get 2-for-1'd by pretty much everything.
And once you use 3+, You may as well just use nightfall to guarantee you can always buff the card. SoPa works too, but it falls into issues.
Of course, this is assuming you're putting nightfalls/momentums into your deck for the sole purpose of activating the soul, although I really doubt this'll just naturally slot into any existing deck.
