Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Rakdos Signet

Dark Ritual

Talisman of Creativity

{T}: Add {C}.
{T}: Add {U} or {R}. Talisman of Creativity deals 1 damage to you.

Crumbling Necropolis

Crumbling Necropolis enters tapped.
{T}: Add {U}, {B}, or {R}.

Talisman of Dominance

{T}: Add {C}.
{T}: Add {U} or {B}. Talisman of Dominance deals 1 damage to you.

Dimir Signet

Command Tower

Izzet Signet

Abaddon the Despoiler

Trample
Mark of Chaos Ascendant — During your turn, spells you cast from your hand with mana value X or less have cascade, where X is the total amount of life your opponents have lost this turn.

Talisman of Indulgence

{T}: Add {C}.
{T}: Add {B} or {R}. Talisman of Indulgence deals 1 damage to you.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.