Have

Golgari Rot Farm

This land enters tapped.
When this land enters, return a land you control to its owner's hand.
{T}: Add {B}{G}.

Bogwater Lumaret

Whenever this creature or another creature you control enters, you gain 1 life.

Jungle Hollow

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {B} or {G}.

Pest Mascot

Trample
Whenever you gain life, put a +1/+1 counter on this creature.

Toxin Analysis

Target creature gains deathtouch and lifelink until end of turn. Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Clue

Marauding Blight-Priest

Whenever you gain life, each opponent loses 1 life.

Forest

Malevolent Rumble

Reveal the top four cards of your library. You may put a permanent card from among them into your hand. Put the rest into your graveyard. Create a 0/1 colorless Eldrazi Spawn creature token with "Sacrifice this token: Add {C}."

Eldrazi Spawn

Essence Warden

Whenever another creature enters, you gain 1 life.

Swamp

Send in the Pest

Each opponent discards a card. You create a 1/1 black and green Pest creature token with "Whenever this token attacks, you gain 1 life."

Sanguine Syphoner

Whenever this creature attacks, each opponent loses 1 life and you gain 1 life.

Riveteers Overlook

When this land enters, sacrifice it. When you do, search your library for a basic Swamp, Mountain, or Forest card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

Blood Researcher

Menace (This creature can't be blocked except by two or more creatures.)
Whenever you gain life, put a +1/+1 counter on this creature.

Germinating Wurm

When this creature enters, you gain 2 life.
Warp {1}{G} (You may cast this card from your hand for its warp cost. Exile this creature at the beginning of the next end step, then you may cast it from exile on a later turn.)

Infuse with Vitality

Until end of turn, target creature gains deathtouch and "When this creature dies, return it to the battlefield tapped under its owner's control."
You gain 2 life.

Pest

Whenever this token attacks, you gain 1 life.

Night's Whisper

Trespasser's Curse

Enchant player
Whenever a creature enchanted player controls enters, that player loses 1 life and you gain 1 life.

Primordial Gnawer

When this creature dies, discover 3. (Exile cards from the top of your library until you exile a nonland card with mana value 3 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Vault Skirge

({B/P} can be paid with either {B} or 2 life.)
Flying
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Nutrient Block

Indestructible (Effects that say "destroy" don't destroy this artifact.)
{2}, {T}, Sacrifice this artifact: You gain 3 life.
When this artifact is put into a graveyard from the battlefield, draw a card.