Baral, as all have said, is a great card. He's a strong engine to power any spell-oriented deck, and at 5/5 for 8 mana he also provides efficient damage.
I typically use him with Kiora or Dovin, with one or two other creatures, 2-4 removal spells, and a few utility cards (other spells or supports).
The Amonkhet/Hour of Devastation sets offer a lot of really good blue spells. Lay Claim is very playable with Baral, since he helps with the 21 mana cost. He will fill the mana of Unsummon or Winds of Rebuke in a single turn, and fill most of the mana of Galestrike. He helps make cycling even more powerful (though it'd be redundant if you have New Perspectives)
As an example, I used this Kiora deck in the "Take 10 or Less Damage" node of the HOD weekend event, and had great success using mostly common and uncommon cards. Of the three rare cards, two didn't really have much impact - Overcome and New Perspectives.Works well on the summon 2 or fewer creatures, too. Baral in general works well with both of those types of objectives.
Dissenter's Deliverance (support removal)
Ambuscade (buff + removal)
Lay Claim (removal)
Hieroglyphic Illumination (draw)
Gather the pack (fetch + discard)
Overcome (buff + removal)
My general strategy with Baral, once he's on the field, is to let his ability charge removal spells and keep them in hand, and use the mana from gem matches to cast other cards. Unless I need a certain spell right away, I just put them in the bottom of my hand and let them charge up passively. In most cases, you'll have a response already prepared to most threats that the AI casts, and will be constantly replenishing your hand.
There are exceptions, of course, and no single card guarantees a win, but Baral can give you a big advantage in most games.