Note that, as with all activated abilities that don't state otherwise, Gisa's works at instant speed as long as they dont have summoning sickness, which means you can spawn blockers during your opponents turn
You must pay X, and for each generic mana in that cost, you may tap an untapped artifact or creature you control rather than pay that mana
The only problem I see in a deck like Valgavoth is if your other draw spells dont come out and over-reliance on Valgavoth as a draw engine is eventually going to catch someones eye
In this, we see the streamer cosied up to Bellibolt another Pokmon shes known to partner with, per the main series Scarlet and Violet games
Gouging Fire ex 204/162 Loading
Let's see what makes each of these decks unique