Farsight Mask

Whenever a source an opponent controls deals damage to you, if Farsight Mask is untapped, you may draw a card.

Search the Premises

Whenever a creature attacks you or a planeswalker you control, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Guardian of the Ages

Defender (This creature can't attack.)
When a creature attacks you or a planeswalker you control, if Guardian of the Ages has defender, it loses defender and gains trample.

Michiko Konda, Truth Seeker

Whenever a source an opponent controls deals damage to you, that player sacrifices a permanent of your choice.

Aurification

Whenever a creature deals damage to you, put a gold counter on it.
Each creature with a gold counter on it is a Wall in addition to its other creature types and has defender. (Those creatures can't attack.)
When Aurification leaves the battlefield, remove all gold counters from all creatures.

Mangara's Equity

As Mangara's Equity enters, choose black or red.
At the beginning of your upkeep, sacrifice Mangara's Equity unless you pay {1}{W}.
Whenever a creature of the chosen color deals damage to you or a white creature you control, Mangara's Equity deals that much damage to that creature.

The Argent Etchings

(As this Saga enters and after your draw step, add a lore counter.)
I — Incubate 2 five times, then transform all Incubator tokens you control.
II — Creatures you control get +1/+1 and gain double strike until end of turn.
III — Destroy all other permanents except for artifacts, lands, and Phyrexians. Exile The Argent Etchings, then return it to the battlefield (front face up).

Elesh Norn

Vigilance
Whenever a source an opponent controls deals damage to you or a permanent you control, that source's controller loses 2 life unless they pay {1}.
{2}{W}, Sacrifice three other creatures: Exile Elesh Norn, then return it to the battlefield transformed under its owner's control. Activate only as a sorcery.