You don't lose unspent mana as steps and phases end.
At the beginning of your end step, if you've spent at least five mana to cast spells this turn, draw a card. If you've spent at least ten, create a 10/10 green Elemental creature token. If you spent at least twenty, you gain 20 life. If you spent at least fifty, you win the game.

As an additional cost to cast this spell, remove any number of counters from among creatures you control. This spell costs {1} less to cast for each counter removed this way.
Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Choose one or more —
• Exile each artifact with mana value X or less.
• Exile each creature with mana value X or less.
• Exile each enchantment with mana value X or less.

[+1]: Draw a card for each different mana value among spells you've cast this turn.
[–X]: Exile target nonland, nontoken permanent with mana value X or less. You create a colorless Saga enchantment token with time loop and “r3— You may cast a copy of the exiled card without paying its mana cost.”
[–8]: You take an extra turn after this one, and each opponent takes an extra turn after the last extra turn. You gain control of each opponent during that player's next turn.

Vigilance, lifelink
Ward—{2}, Pay 2 life.
Azantium, Perfect Creation has all activated abilities and triggered abilities of other artifacts you control.

When this Subroutine enters, you create two 1/1 black Jellyfish enchantment creature tokens with flying, draw two cards, and gain 2 life.
Whenever this Subroutine leaves the battlefield or runs, you sacrifice a creature, discard a card, and lose 1 life.

Exalted, exalted
When this artifact enters, if it was cast, exile target nonland permanent an opponent controls.

When Barbarous Roughrider enters or leaves the battlefield, each opponent loses 2 life unless they sacrifice a nontoken creature.
Wander {4}{B}{B}

Barren Ashlands enters tapped.
{T}: Add {B} or {R}.
{5}{B/R}: Barren Ashlands becomes a 3/3 black and red Lizard creature with first strike until end of turn. It's still a land. This ability costs {X} less to activate, where X is your devotion to black and red. Activate only once each turn.

Lifelink, ward {1}
Whenever Basilo, Lion of Valor attacks, you may bless target nonenchanted creature.

Ward {2}
{U}: Spells you cast this turn can be cast as though they had flash.

Flash
Ward {3}
You may reveal the second card you draw each turn as you draw it. When you do, you may cast it without paying its mana cost. If you didn't cast a spell this way, create two Treasure tokens.

When Berry Fermenter enters, create a Berry token.
{2}, Sacrifice a Berry: You gain 3 life.
{T}, Sacrifice a Berry: Add one mana of any color.

Return any number of target creature cards with total mana value twice X or less from your graveyard to the battlefield. They're artifacts in addition to their other types.

Equipped creature gets +1/+2 and has “At the beginning of your end step, put a time counter on Blade of Bright Futures.”
{2}, Sacrifice Blade of Bright Futures: You gain X life and draw X cards, where X is one plus the number of time counters on it. Activate only as a sorcery.
Equip {2}

Equipped creature gets +2/+1 and has “At the beginning of your end step, put a time counter on Blade of Clouded Pasts.”
{2}, Sacrifice Blade of Clouded Pasts: Target player loses X life and discards X cards, where X is one plus the number of time counters on it. Activate only as a sorcery.
Equip {2}

Enchant player
Enchanted player may cast blue spells with mana value less than or equal to their devotion to blue without paying their mana costs.

Flash
When Blind Keelah enters and whenever you cast a spell during an opponent's turn, each opponent loses 1 life and you surveil 1. This ability triggers only once each turn.

Flying, haste
When Blistering Cryophoenix enters, discard any number of cards, then draw that many cards.
If a spell you own which had its flashback cost paid would be put into exile, put it into your hand instead.

Flying, haste
Whenever you attack, you may pay {R} and sacrifice two artifacts and/or enchantments. If you do, return this card from your graveyard to the battlefield tapped and attacking.

This spell costs {X} less to cast, where X is the number of Mountains you control plus the number of cards with a cycling ability in your graveyard.
Search your library for a Dragon or Phoenix card, put it onto the battlefield, then shuffle.
Mountaincycling {2}

Trample
Breaking Ground must be blocked if able.
{T}: Add {C}.
Spellcharge 9

Creatures you control get +X/+X and gain vigilance and trample until end of turn, where X is the number of Forests you control plus the number of cards with a cycling ability in your graveyard.
Forestcycling {2}

Bring Down the Sky deals X damage to each creature and each planeswalker. Put up to X exiled cards with flashback you own into your graveyard.

Ninjutsu {2}{G}
When this creature enters, another target creature you control gains indestructible until end of turn. Untap it.