Full Shaddoll Aeon
Normal Trap Card
(1) Target 1 "Shaddoll" monster you control; send 1 "Shaddoll" card from your hand to the Graveyard, and if you do, that monster gains 1000 ATK and DEF, but it is changed to face-down Defense Position during the End Phase.
Source: The Organization
On the surface, Full Shaddoll Aeon seems underwhelming as it has only one effect. But the truth is, you can do plenty with this single effect. With only targeting as a cost, the sent Shaddoll card will be able to trigger its grave effect as it is sent there as part of an effect and not part of a cost. This discard, or rather in strict terminology, the sending to the grave process grants Shaddoll users yet another way to dump their cards to the grave to further progress their gameplay.
The attack boost is also appreciated, but do not be misdirected for a second and assume that this card can only be used during the Battle Phase. You can still use it during the Main Phases, both yours and the opponent, in order to trigger effects like a draw of Shaddoll Beast or the destruction of a S/T with Shaddoll Dragon's help.
1000ATK and DEF boost also helps the archetype, which could remain vulnerable to attacking threats upon being flipped face-up to trigger their flip effects. Combined together with the 1900ATK Shaddoll Beast, this deck can now combat threats within the 2900ATK range in battle., such as Archlord Kristya.
On a related note, the card artwork above is Burst Rebirth, which I feel can contribute to the deck in the form of a tech card.
While this card may not be able to substitute the fallen El-Shaddoll Construct, it can surely provide the deck with some advantage to compete in the current meta.
Now that Shaddolls and Qli has new cards added to their family, when will it be Nekroz's turn?