You may have Karina's Substitute enter as a copy of a creature you control, except it's 1/4 and a Toy in addition to its other types.

Equipped creature gets +1/+0.
Whenever equipped creature deals combat damage to a player, put a stun counter on target permanent they control.
Equip {2}

Equipped creature gets +2/-1.
Equip {1}

{1}, {T}: Add one mana of any color.
{2}, Sacrifice Living Compass: Draw a card.

Before equipped creature would assign, deal, or be dealt damage, sacrifice Lum Berry. If you do, equipped creature gets +1/+1 until end of turn.
When you sacrifice Lum Berry, you may exile equipped creature, then return that card to the battlefield under its owner's control. Put a +1/+1 counter on it.
Equip {1}

{2}: Magnetic Mystery gets +1/+0 until end of turn. Activate only as a sorcery.
As long as you control another artifact, Magnetic Mystery has flying.

When Magnetic Snuffler enters, return target Equipment card from your graveyard to the battlefield attached to Magnetic Snuffler.
Whenever you sacrifice an artifact, put a +1/+1 counter on Magnetic Snuffler.

{1}: Untap Magnetling.
{1}: Magnetling can't be blocked by creatures with power 2 or less this turn.
{1}: Choose a card type. Magnetling loses that type until end of turn.
{1}: Magnetling gets +1/-1 or -1/+1 until end of turn.

When Meteorite enters, it deals 2 damage to any target.
{T}: Add one mana of any color.

{2}, Sacrifice Root Fossil: Surveil 3. You may put a land card you surveilled this way from your graveyard onto the battlefield tapped.
Surface {2}{G}. Root Fossil surfaces transformed.

Whenever Reborn Lily attacks, surveil 3. You may put a land card you surveilled this way from your graveyard onto the battlefield tapped.

Equipped creature gets +1/+1.
As long as equipped creature was activated this turn, it gets an additional +2/+2 and can attack as though it were untapped.
Equip {2}

Calmed Battleground enters tapped unless you control a Plains.
{T}: Add {B} or {R}.

Cryptic Reef enters tapped.
{T}: Add {G} or {U}.
{2}{G}{U}, {T}, Sacrifice Cryptic Reef: Draw a card.

Deeplife Cavern enters tapped unless you control a Forest.
{T}: Add {U} or {B}.

Fortress Arena enters tapped.
{T}: Add {R} or {W}.
{2}{R}{W}, {T}, Sacrifice Fortress Arena: Draw a card.

Frigid Highlands enters tapped unless you control an Island.
{T}: Add {R} or {G}.

Gleaming Hot Springs enters tapped unless you control a Mountain.
{T}: Add {W} or {U}.

{T}: Add {C}.
{T}: Surveil 1. Return Mirage Island to its owner's hand.

Ominous Quag enters tapped.
{T}: Add {W} or {B}.
{2}{W}{B}, {T}, Sacrifice Ominous Quag: Draw a card.

{T}: Add {C}.
{3}, {T}, Sacrifice Prickly Dunes: Create two 1/1 green Plant creature tokens. Activate only as a sorcery.

Primal Fissure enters tapped unless you control two or fewer other lands.
{T}, Sacrifice Primal Fissure: Search your library for a basic land card, put it onto the battlefield, then shuffle.

{T}: Add {C}.
{4}: Rumbling Door becomes a 3/3 Golem creature with vigilance. It's still a land.

Serpentine Woods enters tapped.
{T}: Add {B} or {G}.
{2}{B}{G}, {T}, Sacrifice Serpentine Woods: Draw a card.

{T}: Add {C}.
{3}, {T}: Create a 1/1 white Golem creature token. Spend mana of three different colors to activate this ability.
{T}: Put a +1/+1 counter on target creature. It gains flying until end of turn. Activate only as a sorcery and only if you control ten or more permanents.