Card of the Week Contest #232: Grace Under Pressure

Witching Hour
Instant
Target creature you control gains lifelink until end of turn.
Fateful hour — If you have 5 or less life, instead each creature you control gains lifelink until end of turn, and whenever a creature deals combat damage to you this turn, destroy that creature.

kinotherapy :
Pearl of Obsolescence costs  less to cast, where X is the total power if creatures target opponent controls minus the total power of creatures you control.
When Pearl of Obsolescence enters the battlefield, exile target creatures with total power less than X until Pearl of Obsolescence leaves the field.

A sweeper is usually pretty good when you're behind. Of course, it's very conditional.

It has some flexibility as a surprise finisher or to ambush something with up to 4 toughness.

Pyroclasm on the now tertiary flash color of black. Pun in flavortext.
Attachment Deleted

Mirror of Mortality
Artifact
At the beginning of your upkeep, sacrifice Mirror of Mortality. If you do, exchange life totals with target opponent.
: Return Mirror of Mortality from your graveyard to the battlefield.

Loyal Bloodhound
Creature - Hound
Lifelink (Damage dealt by the creature also causes its controller to gain that much life.)
Loyal Bloodhound gets +1/+0 as long as you have less life than another player.
1/1
A man's best friend.

Thanks to fluffydeathbringer for the wording help!

Grand Arbiter Augustine V
Legendary Creature - Human Advisor
Lifelink
Spells your opponents cast cost X more to cast, where X is how many more creatures they control than you.
“That will cost you.”
3/4

Wording feels bizarre, but this is what I’m going with. 

Multi-target?

Tesagk, if all your opponents have a smaller total than you, then this templating will result in a negative value. Would this result in an additional cost instead of a discount? How about:

Pearl of Obsolescence
Enchantment
If the total power of creatures an opponent controls is greater than the total power of creatures you control, this spell costs less to cast, where X is the difference.
When ~ enters the battlefield, exile any number of target creatures with total power X or less until ~ leaves the battlefield.

Note, though, that it isn't necessarily better if an opponent has a greater total than you, because you chose a single value for X. In such a situation it can only even out the board. You can only discount this up to , and you can only exile up to the difference between the total power of your creatures and an opponents'. However, if you want something that can swing things around and actually discount this up to if an opponent has an overwhelming board state, you can consider something like this (if a bit weird for using more than one variable):

Pearl of Obsolescence
Enchantment
If the total power of creatures an opponent controls is greater than the total power of creatures you control, this spell costs less to cast, where Y is the difference.
When ~ enters the battlefield, exile any number of target creatures with total power X or less until ~ leaves the battlefield.