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
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
Your removal and draw suites let you outlast both, with Terror in particular lacking a deep enough threat pool to really oppose you
Dinosaur decks typically focus on winning through combat, so youll have plenty of chances to draw cards whenever your dinos deal combat damage to a player
What the best Sephiroth deck is remains unclear
If you want more written content, make sure to check out our Lorwyn Eclipsed deck techs and be on the lookout for my fun ranking coming soon