Chicken à la King

Whenever a 6 is rolled on a six-sided die, put a +1/+1 counter on each Bird. (You may roll dice only when instructed to.)
Tap an untapped Bird you control: Roll a six-sided die. (Like now.)

Sword of Dungeons & Dragons

Equipped creature gets +2/+2 and has protection from Rogues and from Clerics.
Whenever equipped creature deals combat damage to a player, create a 4/4 gold Dragon creature token with flying and roll a d20 (a twenty-sided die). If you roll a 20, repeat this process.
Equip {2}

Hydradoodle

As Hydradoodle enters, roll X six-sided dice. Hydradoodle enters with a number of +1/+1 counters on it equal to the total of those results.
Reach, trample

Very Cryptic Command

Choose two —
• Counter target black-bordered spell.
• Return target creature to its owner's hand.
• Untap each permanent you control with a watermark.
• Roll two six-sided dice. Target player mills X cards, where X is the total of those results.

Wall of Fortune

Defender
You may tap an untapped Wall you control to have any player reroll a die that player rolled.

Pippa, Duchess of Dice

{2}{G}, {T}: Roll a six-sided die. It becomes a green Die creature token with power and toughness each equal to its result.
{2}{U}, {T}: Reroll any die. (Activate only any time it makes sense.)

Elvish Impersonators

As Elvish Impersonators enters, roll a six-sided die twice. Its base power becomes the first result and its base toughness becomes the second result.

As Luck Would Have It

Hexproof
Whenever you roll a die, put a number of luck counters on As Luck Would Have It equal to the result. Then if there are 100 or more luck counters on As Luck Would Have It, you win the game. (Count both rolls if you reroll a die.)

Krark's Other Thumb

If you would roll a die, instead roll two of those dice and ignore one of those results.