When the recent bannings were announced I was so focused on Modern that I neglected the significant changes in Legacy. Treasure Cruise being banned means a return to the glory days of RUG Delver and its dominance. RUG Delver is my favorite deck of all time and I am excited for my next chance to play it, whenever that may be.
To keep things constant: consider each hand as if you were going first and without knowledge of what the opponent is playing.
RUG Delver is built with 14 mana producing lands total. Having five lands in your opening hand is unacceptable. While playing Delver, games will often end when you have either one or zero lands on the battlefield.
The objective of Delver decks is to apply pressure and then disrupt your opponent. The key point is that the pressure comes first, ideally. This hand may seem attractive because it has six castable spells—nonetheless these spells can be rendered ineffective by a competent opponent. The strength of situational spells like Stifle and Spell Pierce comes when you put your opponent in a position that he or she can not afford to play around such spells and must play into your hand. Yet another reason to mulligan this hand is that it has only one land and no card draw spell. It is quite likely that you will miss your land drop for several turns if you keep.
This hand may appear similar to the first example. Do not be fooled—this hand is excellent. The vast majority of the time Wasteland is a spell that costs 0 mana plus your land drop for the turn. Brainstorm performs at its best when you have superfluous amounts of one resource, such as lands in this hand. With that in mind, you can view this hand as Delver of Secrets, Sinkhole, Ancestral Recall, two lands. I would recommend casting Brainstorm on turn two on your main phase, playing a Misty Rainforest and then casting another spell that turn. If you were to play Wasteland on turn two you will put yourself in a catch-22 situation of either having to wait a full turn to cast Brainstorm, or not utilizing Brainstorm to its fullest effect.
The potential power of a turn-one Delver supported by free counterspells is one of the leading reasons to play RUG Delver in the first place. Imagine that the Gitaxian Probes were replaced with Volcanic Island, Ponder, and Lightning Bolt—this hand would be an instant keep. Unfortunately there is a bit of uncertainty with this hand. When it comes to mulligans you will sometimes be forced to make the choice between two poor options. I often tell people that you can not mulligan to seven, otherwise I would mulligan nearly every hand. I would accept the fact that some percentage of the time you will simply not draw a land, on the other hand when you do draw a land you should be the favorite to win.
Delver decks typically play no more than 12 creatures for a reason: the creatures in this deck require assistance from spells and have diminishing returns in multiples. There are so many matchups where you will have no chance with this hand.
If you knew that you were playing a mirror match, however, I would keep. Green creatures shine in the RUG mirror, even with that in mind, this hand is subpar. This curve of creatures would lose to most Limited decks.
I would be happy to hear if you agree or disagree with any of my assessments. Feel free to share a particularly difficult mulligan decision you had with Delver!
Thanks for Reading,