Attention all Alicebros:
>turn 1: 30 (Tiamat) + 30 (Tiamat) + 20 (append) + 20 (skill-3)
>turn 2: 50 (skill-1) + 20 (Tiamat per-turn charge) + 30 (???)
>turn 3: 20 (Tiamat per-turn charge) + 50 (Skadi) + 30 (???)
Since Alice can use a second 20% self-charge on turns 2 or 3, she only needs a 30% refund on one round and a 10% refund on another.
Compare this to triple Skadi,
>turn 1: 50 (skill-1), 50 (Skadi)
>turn 2: 20 (skill-3), 50 (Skadi) + 30 (???)
>turn 3: 20 (skill-3), 50 (Skadi) + 30 (???)
Alice NEEDS 30% or more refund on both turns, or else she doesn't have enough to NP.
But you should note that she's going to get less refund on wave one when using double Tiamat, since she won't be benefiting from her skill-1 30% NP-generation buff and she'll have less of a Quick buff than the 170% she'd normally have using triple Skadi.
However, for x/1/x nodes recharge is pretty irrelevant, if you do the Bold and Innovative move of putting Tiamat together with Phantasmoon.
>turn 1: 20 (append) + 30 (Tiamat) + 30 (Phantasmoon) + 20 (skill-3)
>turn 2: Phantasmoon NPs
>turn 3: 20 (2 turns of Tiamat per-turn charge) + 35 (living-human charge from Phantasmoon's NP) + 50 (skill-1) - 105
PLUS you could bring a third support like Skadi for another 50% charge
The annoying things are:
1. Phantasmoon is Buster so the Arts/Quick buffs from Tiamat are wasted on her.
2. She'll enter wave 3 with 45% charge, so you can only use her NP a second time if you pick Oberon as a support, which means you don't get to put the extra Quick buff on Alice nor can Arc benefit from Summer Skadi's AoE damage buff on turn 2.
Though, if there were a 50% charge Servant with a non-charge overcharge skill, then Arc would be able to get a full 40% refund from her NP, plus the 10% from Tiamat, which would allow her to NP on turn 3 without Oberon.