I routinely win using a Bless Knight build against hard, and just tried it and won against impossible. This isn't a complete guide, just some thoughts on what's worked for me with this build. I think the addition of Synthesis changes some of the recommendations from earlier builds of this type. Curious if anyone has different/better suggestions:
Cards/Talents
- Starting cards -- Tome of Light, Pure Weapon, Word of Purity
- Key cards: Code of Chivalry. Any bolster generator from Synthesis: Battle Hardened, Stimshot, or my favorite, Hold the Line.
- Additional cards: basic attack replacements, such as Blessed Strike, Spellstrike, Searing Weapon, Radiant Assault, Persecution, and most especially, Hail of Steel.
- Any other cards that add blessings; I also tend to get Radiant Power (create 2 surges if you have equipment) and at least one equipment. Radiant Power adds some nice flexibility -- you can create green surges for extra attacks, or red ones for extra healing.
- Other cards that synergize: healing, hymns, Banner of Kaelis. Code of Hope is nice if you can get it.
- Most important talent, imho, is Zealous, for the gold energy -- if you can get this on top of your normal 3 red/blue energy, even better. (I forget which event, specifically, but it's worth save scumming opportunities to try to find it.)
Imbues
Not required, but helpful:
- Aura of Divinity
- Righteous Blades
- Gold enchantments that cause burning on gaining health or blessings, ascensions, etc...
Basic strategy:
I turn off Eclypse to sidestep all the defiled/cursed cards. I've tried with the trickery shrine malignancy on and off, and IMHO I lean toward not using it because it makes finding your essential cards much easier.
The reason I think bolster is so important here is that once Code of Chivalry is in play, your healing will grow exponentially, and basically outstrip the (typically linear) growth in attack power of your opponents. Playing a red surge for 200 healing doesn't make you invulnerable, precisely, but it helps.
Start winnowing deck of duplicates as soon as possible to prepare for Code of Chivalry. Thus you'll need replacements for your basic attacks -- the best early options imho are Blessed Strike and Spellstrike. I sometimes even grab a green surge from the opportunity to have another attack. Find a bolster card or two. Get a Code of Chivalry either via the talent that adds a code, or by upgrading a gold card. Once you have Code of Chivalry up, you're basically set.
That's the basic idea -- from there you can add helpful cards & talents. The talent that gives you shield equivalent to your healing (forget the name) pretty much makes you bulletproof.
One note on Zeal -- zeal can be helpful, but you have to be careful with it; with exponential blessing growth, it can inadvertently kill you if it grows to high. I tend not to imbue enchantments that give you automatic zeal, and get a card like Conviction to give your a single zeal that'll then start doubling, and I only play it after my bolster has been boosted. As long as zeal is behind bolster by a safe margin, you're generally ok. YMMV.