This technique is a way to optimize the land/spell ratio for decks that are very close between 16 and 17 lands
Many decks rely heavily on their commander either being cast or being in play, and a card that completely locks out your opponents can make for a very unfun game
Sudden Substitution The idea behind Sudden Substitution is to cast a cheap, meaningless spell and swap it for the best creature on board
when newer, better cards come out they usually lose a lot of their value
As is the case with most complex decks, however, it is very rewarding to master the play patterns and win games with this sort of deck, so if you like puzzles and tutoring lands I recommend giving it a try
Journey of Discovery Journey of Discovery lets you get two basics, play two additional lands, or both if you paid 6 mana