Counterspell

Cradle of Safety

Flash
Enchant creature you control
When Cradle of Safety enters, enchanted creature gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)
Enchanted creature gets +1/+1.

Darksteel Citadel

Double Cleave

Target creature gains double strike until end of turn. (It deals both first-strike and regular combat damage.)

Relic of Progenitus

{T}: Target player exiles a card from their graveyard.
{1}, Exile Relic of Progenitus: Exile all graveyards. Draw a card.

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

Eel Umbra

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets +1/+1.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Razortide Bridge

Razortide Bridge enters tapped.
Indestructible
{T}: Add {W} or {U}.

Ancient Den

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Island

Blacksmith's Skill

Target permanent gains hexproof and indestructible until end of turn. If it's an artifact creature, it gets +2/+2 until end of turn.

Seat of the Synod

Mask of Law and Grace

Enchant creature
Enchanted creature has protection from black and from red.

Blue Elemental Blast

Choose one —
• Counter target red spell.
• Destroy target red permanent.

Standard Bearer

While an opponent is choosing targets as part of casting a spell they control or activating an ability they control, that player must choose at least one Flagbearer on the battlefield if able.

All That Glitters

Enchant creature
Enchanted creature gets +1/+1 for each artifact and/or enchantment you control.

Dispel

Benevolent Blessing

Flash
Enchant creature
As Benevolent Blessing enters, choose a color.
Enchanted creature has protection from the chosen color. This effect doesn't remove Auras and Equipment you control that are already attached to it.

Plains

Blighted Agent

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Blighted Agent can't be blocked.

Thraben Inspector

When Thraben Inspector enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Cartouche of Solidarity

Enchant creature you control
When Cartouche of Solidarity enters, create a 1/1 white Warrior creature token with vigilance.
Enchanted creature gets +1/+1 and has first strike. (It deals combat damage before creatures without first strike.)

Thoughtcast

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Draw two cards.

Ichorclaw Myr

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever Ichorclaw Myr becomes blocked, it gets +2/+2 until end of turn.

Ethereal Armor

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

Cartouche of Knowledge

Enchant creature you control
When Cartouche of Knowledge enters, draw a card.
Enchanted creature gets +1/+1 and has flying.