Rejoice! The green Ponder is here!
Pardon my enthusiasm, but I consider it my personal duty to compensate for the collective lack of enthusiasm I’ve seen given to this card from the Cube community.
They’re playing with the color pie! This is exciting stuff! Do you remember when they gave a new form of card advantage to red?
Now, I understand the reservations regarding Oath of Nissa.
1) The Planeswalker Factor
In the abstract, I wouldn’t be inclined to touch a “planeswalkers matters” card with an arbitrarily length-ed pole. That said, the clause about casting planeswalkers is mostly trinket text. The bulk of the card’s utility is as a 1-mana card filtering effect in green! No longer must we longingly gaze at cards like Lead the Stampede and Mulch, wishing they were more efficient and more flexible. We have Oath of Nissa!
2) The “I was burned one too many times by Augur of Bolas” Factor
We’ve all been there. Augur of Bolas’s trigger hits the stack, you’re sitting there rubbing your hands expectantly, only to walk away with the Detroit Lions’ Super Bowl trophy cabinet. “At least I got this 1/3,” you tell yourself, as if it’s some consolation.
But if Oath of Nissa misses, what do you have? Next to nothing. Here’s the trick though: Oath of Nissa doesn’t miss! (Spoiler: it does… unless you’re Cheon.)
How Does Oath of Nissa Perform?
This left us with Oath of Nissa and 39 other cards, 28 of which are eligible targets for the Oath of Nissa’s ETB trigger. Then, I simulated 10,000 samples of 3 cards (from a possible 39), and computed how many of the cards from each 3-card draw were eligible hits for Oath of Nissa (lands, creatures, or planeswalkers).
For this deck, about 80% of our draws will leave us with 2 or 3 eligible cards to choose from. We miss around 2% of the time.
Digging further, I looked at how many of these draws had their “hits” as all lands, all spells (creatures and/or planeswalkers), or a mix of the two:
In total, about half of our Oath of Nissa flips will give us a selection of both lands and spells.
Lastly, I looked at the maximum converted mana cost of the cards “hit” by an Oath of Nissa draw. For, example, if we turned up the following 3 cards, the maximum CMC among hits would be 2, since Growth Spasm isn’t an eligible draw.
If we’re in topdeck mode, Oath of Nissa will hit one of our finishers (4-, 5-, and 6-drops) about 40% of the time. 1/3 of draws yield only lands.
Let’s take a look at another deck.
This deck’s planeswalkers could all benefit from Oath of Nissa’s mana clause, but the deck itself is loaded with misses. If I slot in Oath for, say, Brainstorm, just 23 of the remaining 40 cards are eligible hits.
Even in this relatively worst-case scenario, we miss on only 7% of our triggers.
Oath of Nissa In 40- and 60-Card Decks
To finish, I want to look at how often Oath of Nissa actually misses in Limited and Constructed settings. This probability, naturally, is a function of how densely loaded your deck is with lands, creatures, and planeswalkers.
For this, we define the number of possible hits as the land + creature + planeswalker card count in our deck.
In each case, as long as about 75% of your deck is composed of eligible hits for Oath of Nissa, you’ll only miss about 1% of the time. As you add more non-hits, the miss rate rises fairly quickly.
As a standalone effect, Oath of Nissa introduces powerful and reliable card-filtering to a color historically lacking in that department. Any extra synergies yielded from Oath as an enchantment on the battlefield are just gravy.