This way, you can give protection to the 1/1 token you get from Adeline, Resplendent Cathar, and you can also get the +1+1 counter from Luminarch Aspirant (if you give your creatures protection from white before the trigger, you would not be able to give a counter to one of your creatures)
If you cast Nissa for six mana, now youre making a 6/6, while if you cast Nissa for the full seven mana, you get an 8/8 creature, which are much better payoffs for her ability

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The Force of Will is a bit iffy in this list