Painiac

At the beginning of your upkeep, roll a six-sided die. Painiac gets +X/+0 until end of turn, where X is the result.

Goblin Bookie

{R}, {T}: Reflip any coin or reroll any die. (Activate only any time it makes sense.)

Mountain

Forest

Ground Pounder

{3}{G}: Roll a six-sided die. Ground Pounder gets +X/+X until end of turn, where X is the result.
Whenever you roll a 5 or higher on a die, Ground Pounder gains trample until end of turn.

Ol' Buzzbark

When Ol' Buzzbark enters, roll X six-sided dice onto the battlefield from a height of at least X inches. For each die, put a number of +1/+1 counters equal to the result on each creature you control that die is touching. For each die, Ol' Buzzbark deals damage equal to the result to each creature an opponent controls that die is touching.

Pair o' Dice Lost

Roll two six-sided dice. Return any number of cards with total mana value X or less from your graveyard to your hand, where X is the total of those results. Exile Pair o' Dice Lost.

Lobe Lobber

Equipped creature has "{T}: This creature deals 1 damage to target player or planeswalker. Roll a six-sided die. On a 5 or higher, untap it."
Equip {2}

The Space Family Goblinson

The Space Family Goblinson has trample as long as you've rolled three or more dice this turn.
Whenever you roll a die, put a +1/+1 counter on The Space Family Goblinson.

Growth Spurt

Roll a six-sided die. Target creature gets +X/+X until end of turn, where X is the result.

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

Priority Boarding

Whenever you roll a die, you may reveal the top card of your library. Do this only once each turn. Whenever you reveal a card with mana value less than the result this way, you may exile it. If you do, you may play it this turn.

Resolute Veggiesaur

Trample
Whenever you roll your third die each turn, put a +1/+1 counter on Resolute Veggiesaur.