As with all the reactive cards this is something I try and avoid playing
MTG Shroud rules What does the MTG reminder text say about shroud
While both of these legendary creatures are great, I think Tidus is the better option
On the other hand, there are some non-Niv decks in older formats that could probably use Jegantha, the Wellspring, the question is whether starting with a random 5/5 for five in hand is the best use of a sideboard slot
If you venture into the dungeon while you don't have any dungeons in the command zone, meaning you're not in a dungeon, it's time to start your journey
Morophon was an obvious reprint for the Eldrazi Incursion deck, where it pumps your Eldrazi creatures and makes Ulalek, Fused Atrocity free to cast