Okay...Let's talk spells...

These are the spells I've got in my red deck with a single mana cost:

Lightning Bolt - plain, simple, and cheap. Targets include opponents by the way.

Then there's one of my favorites...

...Firebreathing. Not only is this a great way to avoid Mana Burn, but it can make Wall of Stone do damage when it blocks, increase my Dragon Whelp's power - without destroying it, and make Spikeshot Goblin's spikes more...spikey.

Last but not least, there's Goblin Grenade:

"Sacrifice a Goblin to have Goblin Grenade do 5 damage to one target."

So basically, you give a grenade to any Goblin in play, like Goblin Digging Team or Goblin Balloon Brigade each of which does only 1 point of damage normally, and they'll hold onto it as they (or fly) walk up to whatever target you choose and blow up, causing 5 points of damage instead of one.

Did i mention ow much I love Goblins?