Deck strategy:

Holy Wrath Paladin is a powerful control deck with a strong finishing combo. The many removal options, plentiful card draw and big amount of healing can consistently get the deck to the late game. This deck has an additional combo with Da Undatakah to deal with warriors that can get more life gain than the double combo can do, turning those games in favorable match-ups.

Combo 1: When deck is empty: play Shirvallah, the Tiger -> Baleful Banker her -> Holy Wrath for 25 damage.

Combo 2: 2x Leper Gnome + 1x Immortal Prelate -> Immortal Da Undatakah that deals +4 damage every time it dies (first time = 4, second time is 4+4, third is 4+4+4 etc).

Card explanations:

Leper Gnome: This minion provides an early drop to contest aggro decks while also poking for some damage. It enables Da Undatakah, and as a 1-attack minion it can be tutored with Crystology.

Immortal Prelate: Mainly in the deck to activate its effect for Da Undatakah, but can be used early to contest the board against aggro decks. In slower match-ups avoid playing this card, as it refills the deck again. Try to play it once to maximize the amounts of Leper Gnome effects for Da Undatakah. Running 1 copy is more than enough, as multiple copies make the decks much slower.

Crystology: There are 6 targets in the deck, and Immortal Prelate can be drawn multiple times. Even when there are no targets left it can still activate Wild Pyromancer.

Acolyte of Pain: A minion that can provide multiple draws. In other versions Novice Engineer is used but because this version is less clunky (with only 1 copy of Holy Wrath and no Prismatic Lens) Acolyte is better.

Baleful Banker: Despite only running a single copy of the combo, there are still 2 bankers in the deck. Against aggro it allows you to Shirvallah early and shuffle a copy in the deck, without losing the possibility to do the combo. Against control decks it can be combined with Da Undatakah to play around silence effects.

Alternative versions:

a) If you like this build (no Prismatic Lenses), but you prefer a more standard version with double combo, you can make the following changes:

Da Undatakah -> Bloodmage Thalnos (or Alexstrasza)

Immortal Prelate -> Holy Wrath

Leper Gnomes -> Elven Archers

b) Alternatively, if you don't have Shirvallah, the Tiger or you want to try a pure Da Undatakah version, you could try it out with these changes:

Shirvallah, the Tiger -> Nozari

Holy Wrath -> High Priest Thekal