Origin of Spider-Man

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create a 2/1 green Spider creature token with reach.
II — Put a +1/+1 counter on target creature you control. It becomes a legendary Spider Hero in addition to its other types.
III — Target creature you control gains double strike until end of turn.

Sheltered by Ghosts

Enchant creature you control
When this Aura enters, exile target nonland permanent an opponent controls until this Aura leaves the battlefield.
Enchanted creature gets +1/+0 and has lifelink and ward {2}.

Optimistic Scavenger

Eerie — Whenever an enchantment you control enters and whenever you fully unlock a Room, put a +1/+1 counter on target creature.

Veteran Survivor

Survival — At the beginning of your second main phase, if this creature is tapped, exile up to one target card from a graveyard.
As long as there are three or more cards exiled with this creature, it gets +3/+3 and has hexproof. (It can't be the target of spells or abilities your opponents control.)

Ethereal Armor

Enchant creature
Enchanted creature gets +1/+1 for each enchantment you control and has first strike.

Shardmage's Rescue

Flash
Enchant creature you control
As long as this Aura entered this turn, enchanted creature has hexproof.
Enchanted creature gets +1/+1.

Slumbering Keepguard

Whenever an enchantment you control enters, scry 1.
{2}{W}: This creature gets +1/+1 until end of turn for each enchantment you control.

Plains

Elegant Rotunda

When you unlock this door, put a +1/+1 counter on each of up to two target creatures.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Grand Entryway

When you unlock this door, create a 1/1 white Glimmer enchantment creature token.
(You may cast either half. That door unlocks on the battlefield. As a sorcery, you may pay the mana cost of a locked door to unlock it.)

Grand Entryway // Elegant Rotunda

Seam Rip

When this enchantment enters, exile target nonland permanent an opponent controls with mana value 2 or less until this enchantment leaves the battlefield.

Skyward Spider

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)
This creature has flying as long as it's modified. (Equipment, Auras you control, and counters are modifications.)