Golden Pig Machine

The Golden Pig Machine is an item in Angry Birds Epic that the player gets after passing Level 3 of Golden Fields. It is used to roll for strong weapons and offhand items. The items' strength varies from 0 to 3 stars. Sometimes the items that you've already got are rerolled.

Cheap Roll
The Cheap Roll is worth 3 Lucky Coins. With it you have a normal chance of getting strong items. It fills up the Rainbow Bar by 1/50, so you'd have to do 50 such rolls, which translates into spending 150 Lucky Coins, to completely fill it up.

Expensive Roll
The Expensive Roll is worth 20 Lucky Coins. With it you have a high chance of getting strong items. It fills up the Rainbow Bar by a fifth, meaning you'd have to spend 100 Lucky Coins to get the 5 rolls needed to completely fill it up. It makes sense to spend Lucky Coins on Expensive Rolls than on Cheap Rolls, but you can always choose which rolls to buy.

Rainbow Bar
The Rainbow Bar is a bar that's filled up when doing rolls. The player gets to roll a friend's Golden Pig Machine for free once per day, there's also an option to get a free roll by watching a video ad. The free rolls fill up the Rainbow Bar by as much as the Cheap Roll does. When rolling a friend's Golden Pig Machine, both the player and his/her friend's Rainbow Bars will be filled up. As soon as it's filled up, the player gets a 100% chance of getting a Legendary Set Item with the next roll.

Weapon Strength
Every time you roll, you will get about 0 to 3 stars - the more stars you get, the stronger the weapon is. You can get the same weapon, but it will get stronger based on the stars, if you get rainbow stars, you will get a legendary set item. The bird level is another factor that determines an item's strength, for example, a level 21 Paper (legendary set item) will be more powerful than the Paper that was acquired while being level 15, so it is advised to go for legendary set items when you have reached the maximum level.

Rainbow Riot
In v1.0.12 a period called Rainbow Riot was introduced. During it all your Golden Pig Machine rolls have a 3 times higher chance to get powerful items (that includes legendary set items). The Rainbow Riot starts when you have defeated the Day 7 Golden Pig (so don't forget to beat the Golden Pig every day) and it lasts for 15 minutes. Aside from higher chances, the Rainbow Riot is actually a great time for Cheap Rolls because the chances are that Cheap Rolls will give you more legendary set items than Expensive Rolls. Also, Expensive Rolls will also give you more chance to give you legendary set items than original Expensive Rolls!

Legendary Set Items
Legendary Set Items are special weapons and off-hand items that give you a special bonus when equipped with their specific items like revive, extra damage, heal, etc... Each bird has 6 set items. Aside from giving a special bonus when equipped with their counterparts, the effects and chances of each legendary set item are 50-60% stronger/higher than those of plain items, for example, a plain item has a 15% chance to deal critical damage while a legendary set item has a 23% chance. Another example is that a plain item heals by 10% of dealt damage while a legendary set item heals by 15%. Note that these boosts don't apply to critical strikes and chain attacks, as in, a legendary set item's critical strike will still deal 50% bonus damage, not 75%, the same goes for chain attacks - 50% damage to an additional enemy, not 75%.

Trivia

 * The Candy Bomb (at first it was called Candy Crusher) is a reference to Candy Crush Saga as the ring is made from Candy Crush-shaped-candies.
 * The Candy Chain is a reference to the Color Bomb in.
 * The Artillery Strike is a reference to the Big Lucky in.
 * THE Sling and the Angry Bird Plushies are both references to the original Angry Birds.
 * The Grand Slam also refers to, in sports, the winning of all available major sports or titles in a given year or sports season. It is unknown how is this going to work, because the set effect involves use of Red's weapons.
 * Doom and Demise are related to the Grim Reaper.
 * Sword Spirit has the weapons of Dragontooth and Dragonscale. If you dress up Red as an Avenger, then use Dragontooth and Dragonscale on him, he can be disguised as the Sword Spirit.
 * You may watch a video for one cheap roll, but sometimes the glitch that you didn't watch a full video though you did occurs.
 * Prior to v1.0.14, Matilda's Nightmare set used to deal 200% damage to stunned enemies, and it only worked in the 1st wave. Later the Nightmare set deals 200 damage to stunned enemies and it works in all waves. Now it returned to 200% damage instead of 200 damage.
 * With Matilda's Nightmare set, nightmare applies to all stunned pigs no matter whom stunned by.