Sure, you can easily whiff and hit lands or spells that aren't useful (Counterspell, Comet Storm, etc.) but generally speaking this ability is going to be well worth using
It is a huge mana sink, but with infinite mana or a large amount of it, you mostly guarantee a loss of life enough to kill the table after they run out of permanents
What the best Sephiroth deck is remains unclear
Let our blood be their mulch, our flesh their soil. Victor, Valgavoths seneschal Illustrated by Deruchenko Alexander Standard Legal Alchemy Legal Pioneer Legal Historic Legal Modern Legal Brawl Legal Legacy Legal Comp
The easiest battles to flip, Invasion of Gobakhan and Invasion of Zendikar, each enter play with three defense counters
The only mistake you could make by starting your Lorcana Journey with this deck is not buying a second