(Only the upped shown here, because the upped is way weaker, the unupped is 'just' weaker).
First: Yes, I know that Tall Shadow|Shadow main power is in the Nightfall-Eclipse synergy.
But it's not the main, it's the only usage as a card (and it's a nice token) and in Darkness deck, you'll have enough quanta.
The suggestion is to make it's cost to 1
, what does not affect the Nightfall combo and this card as a token.
Reasons:
It's really useless without the Nightfall, overshadowed by a free (or a negative cost) card (Spark|Ball lightning).
You can't really use with Soul catcher|Mitosis or any buff card without using Darkness quanta (and still will be overshadowed by Ball lightning or Spark).
Spark is still rarely used and Skeleton and Spark has got the 'cost reducton' as buff.
Yes it's still not helps much, but at least gives potential to try this card out in non-Darkness decks.