Combine cost decreased. Mana increased. Slow duration increased. Missile speed increased. Missile spread time decreased.
The old GLP-800 is still a bit on the weak side, and also feels less responsive than we'd like. Some feel-good buffs—as well as a bit more gold efficiency—should be just what the doctor ordered.
COMBINE COST :  ⇒ 450
TOTAL COST : (unchanged, offset by Lost Chapter cost increase)
MANA :  ⇒ 600
SLOW DURATION :  ⇒ 2 seconds
MISSILE SPEED :  ⇒ 2000
MISSILE SPREAD TIME : [0.3] ⇒ 0.2 seconds
CAST TIME : 0.25 seconds (unchanged)
This item is still a bit too weak.
TOTAL COST : [3000 gold] ⇒ 2800 gold
COMBINE COST : [850 gold] ⇒ 650 gold
Active damage and slow increased.
We brought the damage on GLP's active down when we updated it last patch since its component Lost Chapter is more appealing to bursty champs than Catalyst of Aeons, and we didn't want to turn GLP into a must-buy. While we did sidestep that risk, GLP is unappealing to everyone right now. We're upping its damage nerfs to make GLP a more enticing option.
(...Upon further inspection, said damage nerfs missed the patch 8.4 notes. Sorry about that.)
UNDOCUMENTED 8.4 RATIO NERF : [0.35 power prior to 8.4] ⇒ 0.2 ability power in 8.4, unchanged in 8.5
| DAMAGE :
||(at levels 1-18)
SLOW : [40%] ⇒ 65%
This one's for catching.
MANA :  ⇒ 500
|BUILD PATH :
||[Catalyst of Aeons]
||+ Hextech Revolver + 850 gold
HEALTH No longer grants 300 health
ETERNITY Restore mana equal to 15% of damage taken from champions. Restore health equal to 20% of mana spent, up to 15 health per cast, while toggle abilities can heal for up to 15 per second.
COOLDOWN REDUCTION 10%
UNIQUE PASSIVE Haste: This item gains an additional 10% cooldown reduction
LESS FROSTY Frost Bolt now only damages and slows first unit hit (per missile)
LONGER WINTER Frost Bolt slow decays over [0.5] ⇒ 1 second
STRAIGHT AND NARROW Frost Bolt cone narrowed by 10 degrees. Frost Bolt cone range increased by 200
FROST BOLT SLOW PERCENT : [65%] ⇒ 40%
FROST BOLT MISSILE SPEED :  ⇒ 1600
Health restore on mana spend decreased.
Like we said in the above section, Catalyst’s upgrades heal too much once you start getting a big mana pool. Context!
PERCENT MANA TO HEALTH CONVERSION : [0.25] ⇒ 0.2
Activate to spray enemies with icy bolts and slow them.
While back-line artillery or shield-heavy utility mages can load up on ability power in whatever combination to get by (thanks to range or mitigation), mages that get up close and personal are forced to buy whatever will give them the stats to survive combat. Following in Revolver’s footsteps, Hextech remedies this situation by saying ‘If you have to be in the middle of a fight, you should have the extra fire to customize how your encounters play out’.
Enter the GLP-800. Targeted at CC-heavy mages that like to skirmish, GLP provides an extra spell cooldown and source of damage that allows you more in-fight flexibility. Need to peel an ally from a pesky diver? GLP’s got that. Worried you can’t land your combo? GLP can let you hit-confirm your CC and lock opponents down for good. You can even waveclear with it in a pinch! Whatever your particular in-fight need is, the GLP-800’s got your back to enable the beefier mages out there with the tools to get the job done.
TOTAL COST : 3000 gold
BUILD PATH : Hextech Revolver + Catalyst of Aeons + 850 gold
ABILITY POWER : 80
HEALTH : 300
MANA : 400
ETERNITY : UNIQUE Passive - 15% of damage taken from champions is gained as Mana. Spending mana restores 25% of mana spent as Health, up to 25 health per cast (Toggle spells heal for up to 25 per second).
FROST BOLT : UNIQUE Active - Fires a spray of icy bolts that explode, dealing 100-200 magic damage (at levels 1-18). Enemies hit are slowed by 65%, decaying over 0.5 seconds. (40 second cooldown, shared with other Hextech items.)
FROST BOLT RATIO : 0.35 ability power