Bottle Gnomes

Sacrifice Bottle Gnomes: You gain 3 life.

Contemplation

Whenever you cast a spell, you gain 1 life.

Light of Promise

Enchant creature
Enchanted creature has "Whenever you gain life, put that many +1/+1 counters on this creature."

Ratchet, Rescue Racer

Living metal (As long as it's your turn, this Vehicle is also a creature.)
Lifelink
Whenever one or more nontoken artifacts you control are put into a graveyard from the battlefield, convert Ratchet. This ability triggers only once each turn.

Ratchet, Field Medic

More Than Meets the Eye {1}{W} (You may cast this card converted for {1}{W}.)
Lifelink
Whenever you gain life, you may convert Ratchet. When you do, return target artifact card with mana value less than or equal to the amount of life you gained this turn from your graveyard to the battlefield tapped.

Ratchet, Field Medic // Ratchet, Rescue Racer

Conjurer's Bauble

{T}, Sacrifice Conjurer's Bauble: Put up to one target card from your graveyard on the bottom of your library. Draw a card.

Grinding Station

{T}, Sacrifice an artifact: Target player mills three cards.
Whenever an artifact enters the battlefield, you may untap Grinding Station.

Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Scrapheap

Whenever an artifact or enchantment is put into your graveyard from the battlefield, you gain 1 life.

Blind Obedience

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Artifacts and creatures your opponents control enter the battlefield tapped.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Soul Warden

Whenever another creature enters the battlefield, you gain 1 life.

Junk Diver

Flying
When Junk Diver dies, return another target artifact card from your graveyard to your hand.

Treasure Chest

{4}, Sacrifice Treasure Chest: Roll a d20.
1 | Trapped! — You lose 3 life.
2—9 | Create five Treasure tokens.
10—19 | You gain 3 life and draw three cards.
20 | Search your library for a card. If it's an artifact card, you may put it onto the battlefield. Otherwise, put that card into your hand. Then shuffle.

Arcbound Ravager

Sacrifice an artifact: Put a +1/+1 counter on Arcbound Ravager.
Modular 1 (This creature enters the battlefield with a +1/+1 counter on it. When it dies, you may put its +1/+1 counters on target artifact creature.)

Pit Trap

{2}, {T}, Sacrifice Pit Trap: Destroy target attacking creature without flying. It can't be regenerated.

Mishra's Bauble

{T}, Sacrifice Mishra's Bauble: Look at the top card of target player's library. Draw a card at the beginning of the next turn's upkeep.

Urza's Bauble

{T}, Sacrifice Urza's Bauble: Look at a card at random in target player's hand. You draw a card at the beginning of the next turn's upkeep.

Cogworker's Puzzleknot

When Cogworker's Puzzleknot enters the battlefield, create a 1/1 colorless Servo artifact creature token.
{1}{W}, Sacrifice Cogworker's Puzzleknot: Create a 1/1 colorless Servo artifact creature token.

Auriok Champion

Protection from black and from red
Whenever another creature enters the battlefield, you may gain 1 life.

Scroll of Avacyn

{1}, Sacrifice Scroll of Avacyn: Draw a card. If you control an Angel, you gain 5 life.

Shattered Angel

Flying
Whenever a land enters the battlefield under an opponent's control, you may gain 3 life.

Alchemist's Vial

When Alchemist's Vial enters the battlefield, draw a card.
{1}, {T}, Sacrifice Alchemist's Vial: Target creature can't attack or block this turn.

Astrolabe

{1}, {T}, Sacrifice Astrolabe: Add two mana of any one color. Draw a card at the beginning of the next turn's upkeep.

Fountain of Renewal

At the beginning of your upkeep, you gain 1 life.
{3}, Sacrifice Fountain of Renewal: Draw a card.

Authority of the Consuls

Creatures your opponents control enter the battlefield tapped.
Whenever a creature enters the battlefield under an opponent's control, you gain 1 life.

Scroll of Griselbrand

{1}, Sacrifice Scroll of Griselbrand: Target opponent discards a card. If you control a Demon, that player loses 3 life.

Sunbeam Spellbomb

{W}, Sacrifice Sunbeam Spellbomb: You gain 5 life.
{1}, Sacrifice Sunbeam Spellbomb: Draw a card.

Soul's Attendant

Whenever another creature enters the battlefield, you may gain 1 life.

Dispeller's Capsule

{2}{W}, {T}, Sacrifice Dispeller's Capsule: Destroy target artifact or enchantment.

Workshop Assistant

When Workshop Assistant dies, return another target artifact card from your graveyard to your hand.

Ingenious Smith

When Ingenious Smith enters the battlefield, look at the top four cards of your library. You may reveal an artifact card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
Whenever one or more artifacts enter the battlefield under your control, put a +1/+1 counter on Ingenious Smith. This ability triggers only once each turn.

Scrap Trawler

Whenever Scrap Trawler or another artifact you control is put into a graveyard from the battlefield, return to your hand target artifact card in your graveyard with lesser mana value.

Golem's Heart

Whenever a player casts an artifact spell, you may gain 1 life.

Sunscorch Regent

Flying
Whenever an opponent casts a spell, put a +1/+1 counter on Sunscorch Regent and you gain 1 life.

Claws of Gix

{1}, Sacrifice a permanent: You gain 1 life.

Orim's Prayer

Whenever one or more creatures attack you, you gain 1 life for each attacking creature.

Salvager of Ruin

Sacrifice Salvager of Ruin: Choose target permanent card in your graveyard that was put there from the battlefield this turn. Return it to your hand.

Voyager Staff

{2}, Sacrifice Voyager Staff: Exile target creature. Return the exiled card to the battlefield under its owner's control at the beginning of the next end step.

Voice of the Blessed

Whenever you gain life, put a +1/+1 counter on Voice of the Blessed.
As long as Voice of the Blessed has four or more +1/+1 counters on it, it has flying and vigilance.
As long as Voice of the Blessed has ten or more +1/+1 counters on it, it has indestructible.

Myr Scrapling

Sacrifice Myr Scrapling: Put a +1/+1 counter on target creature.

Potion of Healing

When Potion of Healing enters the battlefield, draw a card.
{W}, {T}, Sacrifice Potion of Healing: You gain 3 life.

Triangle of War

{2}, Sacrifice Triangle of War: Target creature you control fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Citizen's Crowbar

When Citizen's Crowbar enters the battlefield, create a 1/1 green and white Citizen creature token, then attach Citizen's Crowbar to it.
Equipped creature gets +1/+1 and has "{W}, {T}, Sacrifice Citizen's Crowbar: Destroy target artifact or enchantment."
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Moonglove Extract

Sacrifice Moonglove Extract: It deals 2 damage to any target.

Nykthos Paragon

Whenever you gain life, you may put that many +1/+1 counters on each creature you control. Do this only once each turn.

Twinblade Paladin

Whenever you gain life, put a +1/+1 counter on Twinblade Paladin.
As long as you have 25 or more life, Twinblade Paladin has double strike. (It deals both first-strike and regular combat damage.)

Attended Healer

Whenever you gain life for the first time each turn, create a 1/1 white Cat creature token.
{2}{W}: Another target Cleric gains lifelink until end of turn.

Implement of Improvement

{W}, Sacrifice Implement of Improvement: You gain 2 life.
When Implement of Improvement is put into a graveyard from the battlefield, draw a card.

Myr Retriever

When Myr Retriever dies, return another target artifact card from your graveyard to your hand.

Ajani's Pridemate

Whenever you gain life, put a +1/+1 counter on Ajani's Pridemate.

Phyrexia's Core

{T}: Add {C}.
{1}, {T}, Sacrifice an artifact: You gain 1 life.

Leonin Elder

Whenever an artifact enters the battlefield, you may gain 1 life.

Syndic of Tithes

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)