Tips ripped straight out of my Notepad. Without any of that fancy 'user-friendly' nonsense.

Deck
2 March of Wretched Sorrow (NEO) 111
Massive late-game life gain

2 Sunset Revelry (MID) 38
Use the tokens from Sunset Revelry!
Consider your opponent's life total and your card count after an Invoke Despair on turns you play the card.
Invoke Despair affects all three modes of Sunset Revelry. Any turn you are looking to cast both, consider how many cards, creatures, and how much life your opponent will have after an Invoke Despair, and how it affects the value you get from Sunset Revelry

3 Caves of Koilos (DMU) 244
3 Go for the Throat (BRO) 102
Try replacing one with Sheoldred's Edict when ONE is released
2 Shigeki, Jukai Visionary (NEO) 206
Don't cast, only channel
Count your mana sources regularly

4 Tear Asunder (DMU) 183
Great for hitting Bankbuster, Mechanized Warfare, Underdog, Squee, and many artifact creatures.

2 Dryad's Revival (MID) 183

Sometimes you may want to forego going for lethal to lock down your attrition game.
Other times you want to forego the attrition game and push through lethal.
Or you can get a little of both.

You have two strategies:
A) Grab Invoke Despair to push two more in over the next two turns (late game, three mid)
I.e. Revival -> Retrieve and cast Invoke -> Flashback Revival -> Retrieve and cast Invoke
B) Revival -> R&C Invoke -> Flashback Revival -> R&C Shigeki -> Retrieve Invoke + Others
C) Grab Shigeki to grind the opponent out. Next turn, Shigeki, turn after Invoke, Revive, Invoke

2 The Celestus (MID) 252
Keeps removal flowing late-game when it matters. Replace your lands.
Try to consider the ways you can manipulate the day/night cycle.

4 Depopulate (SNC) 10

4 Invoke Despair (NEO) 101
consider your opponent's life total after an Invoke Despair
Draw 0-2 spells with Invoke. Totaling 1-3 extra graveyard targets per cast.

2 By Invitation Only (VOW) 5
Indestructible (Benalia girl, Titan of Industry, Sanctuary Warden)

1 Titania's Command (BRO) 194
Life gain, ramp, exile, late game beater

4 Scoured Barrens (NEO) 274
4 Shattered Sanctum (VOW) 264
4 Deathcap Glade (VOW) 261
2 Llanowar Wastes (BRO) 264
2 Jungle Hollow (IKO) 249
3 Crystal Grotto (DMU) 246
**WARNING**
As long as you have a Crystal Grotto on the battlefield, you will need to pay close attention to the auto-tapper. In particular, be sure to tap them to pay for Shigeki, Dryad's Revival, and activating The Celestus.

1 Dig Up (VOW) 197
Can be a land early game
Can fetch Shigeki, revival, or invoke late game
Fetched Shigeki and Revival can bring back Dig Up to grab the other and activate the engine. Keep in hand if you plan to exile graveyards with Farewell to rebuild your combo fast. Once your basic loop is online, use it again to fetch Invoke and begin looping that every turn.
Provides a repeatable option to fetch additional cards each loop

2 Farewell (NEO) 13

1 Portal to Phyrexia (BRO) 240
Can replace with a White Sun's Twilight at ONE release

2 Swamp (SLD) 1132
3 Union of the Third Path (BRO) 31
Synergizes with itself - Replaces itself to keep your hand count high for the next one.
Use after Invoke Despair to boost the life gained by up to 3
Shigeki on your opponent's end step to bypass the hand size limit. Cast Union after you draw your card on your turn (and after an Invoke Despair, if possible) to gain massive life.
Great to fetch back from the graveyard.
Over half your cards (31) go to the graveyard when they resolve. Meaning half the time you will get another target for Shigeki.

1 Plains (NEO) 293

Opponents:
Jin Gitaxias: March of Wretched Sorrow for zero. Dig Up and Sunset are other cheap options for eating the ability.
Farewell - Play around this. Careful not to leave too many Invokes in your GY if oppo playing white