Fill large roasting pan halfway full of water; set aside.
Gently pull back husks from corn, and remove silks but not husks.
Place corn in roasting pan, and add more water until corn is covered. Soak corn for 4 hours, and up to overnight.
minutes before smoking, prepare your smoker by adding soaked wood chips or pellets, and preheat to 225 degrees F.
Remove corn from water and place on paper towels to dry.
In small bowl whisk together butter, brown sugar, paprika, onion powder, garlic powder, and salt. Brush corn with butter mixture, and sprinkle with green onions.
Gently pull husks back over corn. Smoke for 60 minutes, turning once with long grilling tongs during smoking. Let the corn sit 10 minutes, and then pull husks back and serve. Garnish with sliced green onion if desired.