Soulfire Grandmaster is a card I misjudged on first evaluation. I thought it was more of an aggro card that scaled well into the late game however it is turning out to be much more of a control beast. Much like Isochron Scepter it lets you repeatedly use a spell to hard or soft lock down a game. Unlike Isochron Scepter it is not dead on its own, does not make you vulnerable to two for ones, does not exile your spells and does give you a much broader range of spells you can abuse. You can even cast the same spell several times per turn if you have the mana! Certainly Soulfire Grandmaster is much more mana intensive than Isochron Scepter but all the other perks make the Grandmaster the much better card. Just being useful on its own is so important. Needing at least four mana, usually more like seven, to get him going is no big deal. Control decks are trying to get to that sort of stage in the game anyway. A 2/2 super lifelinker that your opponent is terrified of will be getting a lot of work done in the early game as well.
Obviously with his costings Soulfire Grandmaster naturally slots into a Jeskai control deck but any UW base comfortably supports him. I recently got pretty handed by an Esper list packing it. Mostly it was Cryptic Command shutting down my attacks that ended the game but repeat Vindicates on my stuff and Esper Charms in my draw step also did a lot of work! A card that is a fine two drop yet pretty much says win the game if you have it in play with a load of mana and the appropriate card to cast with it is just nutty good. Here is an example list of a standard Jeskai inevitability control deck using Grandmaster.
Swords to Plowshares
Elixir of Immortality
Fire / Ice
Wall of Omens
Jace, Architect of Thought
Elspeth, Sun's Champion
Ugin, the Spirit Dragon
Bonfire of the Damned
Lots of other cards obviously go in this deck as well, Timayo is great and is very much in keeping with the theme of the deck. Force of Will and Snapcaster Mage are always good but do exile cards which can get uncomfortable in some matchups. Sun Titan is a good way to add security to your deck should you be afraid of having your Elixir stripped from your hand or killed when you tap out. Overall the Elixir is your most important card as it gives you the total inevitability however you don't much want to draw it, certainly not early when all it does is put itself at risk of getting killed so to speak. This is part of why you want Brainstorm and Lat-Nam's Legacy in such decks, both to protect Elixir against discard and to negate the ill effects of drawing it early. Karn is another good card as he adds to your total of exile removal effects which are incredibly potent against a lot of the high endurance decks. I am not overly into running 3+ planewalkers that cost 6+ mana in decks without ramp and that ideally like to leave countermagic mana open each turn even with card quality effects.
Non-black control decks used to struggle against planeswalkers resolving. Red could sometimes burn them down but usually this was at the cost of taking a two for one or worse on the resolved walker. With Council's Judgement on top of the burn, some bounce, Ugin and the lovely Mantis Rider this particular non-black control deck does just fine against planeswalkers. As so many of your spells are cheap and/or instant yet do a lot of work combined with the various sources of lifegain you have in the deck you are much less often in a position where you are tapped out and forced to let a planeswalker resolve. Usually what happens is you don't have the counterspell although this is quite a lot better as people are often too scared to run their walker into the potential for countermagic.
Wing Shards is a bit of an odd card in the deck when you have loads of great Wrath options open to you as well as cheaper spot removal (Path to Exile I have found to be good...). The reason behind it is down to diversity of solutions. You need to be able to deal with everything that is thrown at you. Hexproof and indestructible effects are very demanding on your removal and require you to have exactly the right thing. Wingshards sits in a lovely middle ground where it is a bit like a Wrath of God and a bit like Swords to Plowshares and really helps you to deal with problem cards.
As with Isochron Scepter decks, you very rarely ever need to win a game. Just so long as you can win most of the time people will save themselves a lot of pain and scoop well before it comes to that. All you need to do is live, survive and stall! Eventually you will have killed and exiled all their threats, shut them down with a Soulfire Grand Master or just be chain casting Sphinx's Revs and Elixirs gaining more life than you could lose!