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Heartstone

Artifact

Activated abilities of creatures cost {1} less to activate. This effect can't reduce the mana in that cost to less than one mana.

CMC
3
Mana cost
{3}
Color identity
C
Rarity
uncommon
Set
The List
Price
$3.12
EDHREC rank
#3902
Buy on TCGplayer
Heartstone card art
Heartstone cuts the activation cost of any creature ability by one generic mana — and in a format full of commanders who live on repeated tap or pay abilities, that discount compounds fast. Sliver Queen making tokens for one mana instead of two, or Grenzo, Dungeon Warden flipping cards for one mana instead of two, turns a slow engine into something that threatens every turn cycle.

Best Commanders

Commanders with the highest synergy

01
Grenzo, Dungeon Warden

Grenzo, Dungeon Warden

67.4% of decks · synergy 0.65

Grenzo, Dungeon Warden's activated ability already costs just two mana, so Heartstone cutting that to one means you're firing it twice as often on the same budget — the deck's whole game plan is iteration count, and Heartstone doubles it.

02
Ashling the Pilgrim

Ashling the Pilgrim

59.4% of decks · synergy 0.59

Ashling the Pilgrim needs to stack charge counters repeatedly before going nuclear, and every activation costs mana; Heartstone shaves one off each trigger, letting Ashling grow faster and reset sooner after the board wipe.

03
Xantcha, Sleeper Agent

Xantcha, Sleeper Agent

57.1% of decks · synergy 0.55

Xantcha, Sleeper Agent's card-draw ability is the political engine opponents keep activating, but you're the one who benefits — Heartstone makes that activation cheaper for everyone at the table, accelerating the damage and draw loops Xantcha decks are built around.

04
Urza, Prince of Kroog

Urza, Prince of Kroog

35.2% of decks · synergy 0.35

Urza, Prince of Kroog animates artifacts for a cost that scales up fast; Heartstone trims one generic off each animation, making it viable to suit up multiple artifacts in a single turn without tapping out.

05
Emiel the Blessed

Emiel the Blessed

26.9% of decks · synergy 0.26

Emiel the Blessed blinks a creature for three mana, and Heartstone brings that to two — the difference between flickering once per turn and flickering twice, which is the gap between a fair value engine and a broken one.

Format Analysis

Where it lives, where it can’t

FormatVerdict
commander legal
legacy legal
modern not legal
pioneer not legal
standard not legal
vintage legal
pauper not legal
oathbreaker legal

Heartstone is a Commander card in practice — the format's singleton rule and emphasis on commander-centric engines are exactly where a static cost-reduction effect earns its slot. Outside Commander, it's legal in Legacy, Vintage, and Oathbreaker, but those formats either move too fast for a three-mana artifact with no immediate impact or simply lack the activated-ability density to justify it. In Oathbreaker it can replicate the same commander-synergy logic at a smaller scale. Anywhere else, it doesn't show up.

Key Combos

Combo lines featuring this card

Price Context

Current price

$3.12 cheap tier

At $3.12, Heartstone sits in the cheap tier — low enough to include without budget math, but priced just above bulk because its combo and synergy applications keep demand steady. It's not a card that spikes, but it also doesn't fall to bulk bin prices given how consistently it shows up in Grenzo, Xantcha, and Ashling lists.

Explore

Sources

Mentioned

← All cards

Updated . Data from Scryfall, EDHREC, and Commander Spellbook.