Essentially, Revival's mid game revolves around taking 4 bases, getting up to 70-80 drones, and maxing out on muta/ling/bling by 14:00-15:00 to hit a massive timing attack. While this is nothing new, I'm beginning to see this timing used everywhere by Zerg players, and I'm fascinated by it. In other words, this is not an individual, unique timing; however, it is a solid way to play the mid game and exemplified by Revival's play.
VoDs:
Revival vs. Jjakji G2 on Frost
Revival vs. Jjakji G3 on Habitation Station
Since Revival gets into the mid game in a variety of ways and ZvT in general has a lot of room for slight variants on all builds, it will suffice to say that essentially Revival's early game consists of:
- an economic early expansion with early ling speed
- a decently timed 3rd base (~6:00-6:30)
- lair before upgrades
- an emphasis on creep spread
The following benchmarks are based on a composite number from several ZvTs from both Life and Revival + custom games against the computer with no pressure:
@6:00 -> 44 supply/32 drones
3rd hatch @6:30
Lair finishes @8:00
@8:00 -> 70 supply/50 drones
4th hatch @10:00
@10:00 -> 105 supply/70 drones
2/2 upgrades complete @14:00
@14:00 -> maxed/80 drones
Revival almost always gets his lair before upgrades in order to get his mutalisk count up very quickly in order to deal with drops. He uses his mutalisks strictly defensively in the early parts of the mid game. His strong emphasis on creep spread early allows him to also deal with frontal assaults fairly easily. The result is mutalisks taking care of the skies, creep and limited numbers of ling/bane taking care of the ground. This double defense generally allows him to take a fairly safe 4th without fear of losing it.
With good defense, Revival can get all the way up to 80 drones (about 3.5 bases of saturation) on his 4 bases. The 4th base is very important for the slight extra gas income; more gas income = more mutas/banes in the maxed out attack. That said, if you're gas income is suffering some and/or you can't quite defend the 4th base well enough, you should still be able to hit your 14:00 timing, but with less banelings and mutalisks.
Ironically, getting late upgrades does not affect his timing attack, as his upgrades normally complete at 14:00 and coincide perfectly with his maxout timing. Revival always aims the attack directly at the Terran army near the natural with the intent of killing all or most of the army. It's important to note that 14:00 is also the time period that Terran's 2/2 is getting close to finishing, extra rax have just finished, and the Terran attacking machine is about to kick into action. This creates an interesting dilemma for the Terran player by either 1) forcing them to play defensive when they want to be aggressive or 2) being completely blind-sided as they're moving out to be aggressive.
Often times this attack will just outright win the game as the Zerg player can get right on top of the production structures. However, in case it doesn't, Revival generally goes hive behind it. By setting up his hive transition so early, Revival can buy time with the attack and subsequent ling/muta harassment to catch up in upgrades and get ultralisks on the field.
All in all, it's a very powerful and straightfoward timing. The key to achieving success with this mid game style is not taking too much damage from reaper, hellion, or banshee harassment as well as holding off the initial drops without incurring a lot of damage. This requires a lot of strong fundamentals and early game understanding and scouting. Again, it must be emphasized that this timing coincides with the time period when Terran wants to push, creating an anti-timing for the Terran

GL HF!
Bonus notes: + Show Spoiler +
ZvT notes:
Revival vs. Jjakji G1
Alterzim Stronghold
IEM WC 2014
15h16p15g
reaper pressure
@6:00 put back on gas
3rd hatch @6:15
Roach/bane bust @9:00
muta/ling followup
4th hatch @11:00
@6:00 44 supply/36 drones
@10:00 93 supply/48 drones
@14:00 147 supply/72 drones
@16:00 maxed
Revival vs. Jjajki G2
Frost
IEM WC 2014
15h16p15g
@6:00 drones back in gas
3rd hatch @5:50
Lair before upgrades
4th hatch @9:00
NO PRESSURE
muta/ling maxed attack ~14:30
@6:00 44 supply/37 drones
@10:00 106 supply/75 drones
@14:00 maxed/85 drones
Revival vs. Jjakji G3
Habitation Station
IEM WC 2014
triple hatch -> pool
triple gas @5:45
hellion pressure
lair before upgrades
4th hatch @11:00
muta/ling maxed attack ~15:00
@6:00 40 supply/28 drones
@8:00 62 supply/47 drones
@10:00 91 supply/60 drones
@14:00 164 supply/77 drones
Revival vs. Jjakji G4
Heavy Rain
IEM WC 2014
15h16p15g
reaper pressure
@6:00 drones back in gas
3rd hatch @6:30
lair before upgrades
hellion/banshee pressure
@6:00 44 supply/28 drones
@8:00 66 supply/41 drones
@10:00 79 supply/55 drones
Revival vs. Jjakji G5
Daedalus Point
IEM WC 2014
15h16p15g
@5:30 drones back in gas
Fast lair
3rd hatch @7:15
NO PRESSURE
@6:00 44 supply/34 drones
@8:00 68 supply/45 drones
@10:00 102 supply/54 drones
Life vs. TaeJa G1
Heavy Rain
IEM WC 2014
15h15p14g
reaper pressure
@6:30 drones back on gas
3rd hatch @6:45
lair before upgrades
hellion/banshee pressure
4th hatch @11:00
@6:00 40 supply/28 drones
@8:00 61 supply/42 drones
@10:00 83 supply/56 drones
@14:00 151 supply/78 drones
Life vs. TaeJa G2
Yeonsu
IEM WC 2014
15p15h
reaper pressure
double gas @5:45
3rd hatch @6:15
lair before upgrades
4th hatch @11:00
@6:00 46 supply/32 drones
@8:00 70 supply/47 drones
@10:00 100 supply/69 drones
@14:00 143 supply/80 drones
Life vs. TaeJa G4
Frost
IEM WC 2014
15h16p17h
VERY fast 3rd
double gas @6:00
upgrades before lair
hellion/banshee pressure
4th hatch @10:00
@6:00 45 supply/34 drones
@8:00 75 supply/54 drones
@10:00 99 supply/71 drones
@14:00 130 supply/81 drones
Revival vs. Jjakji G1
Alterzim Stronghold
IEM WC 2014
15h16p15g
reaper pressure
@6:00 put back on gas
3rd hatch @6:15
Roach/bane bust @9:00
muta/ling followup
4th hatch @11:00
@6:00 44 supply/36 drones
@10:00 93 supply/48 drones
@14:00 147 supply/72 drones
@16:00 maxed
Revival vs. Jjajki G2
Frost
IEM WC 2014
15h16p15g
@6:00 drones back in gas
3rd hatch @5:50
Lair before upgrades
4th hatch @9:00
NO PRESSURE
muta/ling maxed attack ~14:30
@6:00 44 supply/37 drones
@10:00 106 supply/75 drones
@14:00 maxed/85 drones
Revival vs. Jjakji G3
Habitation Station
IEM WC 2014
triple hatch -> pool
triple gas @5:45
hellion pressure
lair before upgrades
4th hatch @11:00
muta/ling maxed attack ~15:00
@6:00 40 supply/28 drones
@8:00 62 supply/47 drones
@10:00 91 supply/60 drones
@14:00 164 supply/77 drones
Revival vs. Jjakji G4
Heavy Rain
IEM WC 2014
15h16p15g
reaper pressure
@6:00 drones back in gas
3rd hatch @6:30
lair before upgrades
hellion/banshee pressure
@6:00 44 supply/28 drones
@8:00 66 supply/41 drones
@10:00 79 supply/55 drones
Revival vs. Jjakji G5
Daedalus Point
IEM WC 2014
15h16p15g
@5:30 drones back in gas
Fast lair
3rd hatch @7:15
NO PRESSURE
@6:00 44 supply/34 drones
@8:00 68 supply/45 drones
@10:00 102 supply/54 drones
Life vs. TaeJa G1
Heavy Rain
IEM WC 2014
15h15p14g
reaper pressure
@6:30 drones back on gas
3rd hatch @6:45
lair before upgrades
hellion/banshee pressure
4th hatch @11:00
@6:00 40 supply/28 drones
@8:00 61 supply/42 drones
@10:00 83 supply/56 drones
@14:00 151 supply/78 drones
Life vs. TaeJa G2
Yeonsu
IEM WC 2014
15p15h
reaper pressure
double gas @5:45
3rd hatch @6:15
lair before upgrades
4th hatch @11:00
@6:00 46 supply/32 drones
@8:00 70 supply/47 drones
@10:00 100 supply/69 drones
@14:00 143 supply/80 drones
Life vs. TaeJa G4
Frost
IEM WC 2014
15h16p17h
VERY fast 3rd
double gas @6:00
upgrades before lair
hellion/banshee pressure
4th hatch @10:00
@6:00 45 supply/34 drones
@8:00 75 supply/54 drones
@10:00 99 supply/71 drones
@14:00 130 supply/81 drones