This deck is a work-in-progress, but has been a blast to play already. The real power and most common win condition comes from getting multiple copies of [Calamity Bearer] in play, with each copy doubling the damage dealt by giants. Getting three copies on board is not difficult, thanks to [Invasion of the Giants] dropping the cost of a giant spell by two generic, and [Glasspool Mimic] giving you copies for two and a blue. With multiple copies on board, [Battle of Frost and Fire] can sweep the board of non-Giant creatures and planeswalkers, clearing your way for an instant kill, or play [Shatterskull Charger] as a hasty trampler. [Quakebringer] is another powerful card that I will probably run 4 copies of eventually. It keeps dealing damage each upkeep, even from the graveyard, which gets amplified if you have those Calamity Bearers on board. 

In addition to the big Saga sweeper, the deck also has plenty of cheap removal on board to help you get to mid/late make. [Shock] and [Bonecrusher Giant] are ubiquitous in standard red decks, and [Shatterskull Smashing] is there as removal or land as needed. I find [Squash] to be particularly useful in this deck, allowing you to deal 6 damage to any creature or planeswalker for only 1 and a red once you have a giant on board. Having Bonecrusher Giant and [Aegar, the Freezing Flame] in this deck, gives you that cheap option as early as turn 3, helping you deal with those pesky [Ruin Crab] and rogue decks.  

Both Sagas give you scry / card draw, as does [Glimpse the Cosmos], which you can cast a second time from your graveyard for one blue as long as you control a giant. 

The deck is susceptable to control decks, with no direct answers for counterspells/removals. However, you'll usually be able to keep on the pressure by finding the giants you need and getting them on board for cheap. [Shatterskull Charger] also lets you avoid some removal tricks, as it gets returned to your hand at end of turn if you cast without kicker and it doesn't get a +1/+1 counter. Cast and attack when your opponent is tapped out, then bounce him safely back to your hand before your opponent's upkeep.