Some noncreature spells that greatly benefit from shapeshifters are cards like Harmonized Crescendo, The Bears of Littjara, and Peer Pressure
If you want to make a competitive deck, you need dual lands, fetch lands, and other extremely OP staples
This gives you multiple creatures to Polymorph, as trading a 1/1 for a powerful creature is what makes Polymorph so great
Finally, acetate offers a clear view of both sides of the card which is great for collecting games where double sided information matters most
The result is that if you can land both on the field you can fire the ballista ad nauseam, stacking counters on it and taking them off to inflict infinite damage and gain infinite life
Frontier Bivouac Frontier Bivouac provides multicolor decks with really cheap, effective fixing