Cheapest priced copy (Modern Horizons 3 Commander): $0.49 at Card Kingdom, near mint, their price list as of .
Deepfathom Skulker 
Creature — Eldrazi · 4/4 · Rare · Oath of the Gatewatch · #43
Devoid (This card has no color.)
Whenever a creature you control deals combat damage to a player, you may draw a card.
{3}{C}: Target creature can't be blocked this turn. ({C} represents colorless mana.)
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
4 printings · $0.49 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Modern Horizons 3 Commander | 180 | Rare | $0.49 | $0.49 |
| Oath of the Gatewatch | 43 | Rare | $0.49 | $0.79 |
| Oath of the Gatewatch Promos | 43 | Rare | — | $0.99 |
| Oath of the Gatewatch Promos | 43s | Rare | — | $1.49Out of stock |
One ruling from Wizards of the Coast
- 22 January 2016Activating Deepfathom Skulker’s last ability after it’s been legally blocked won’t change or undo that block. The declare attackers step is the last time you can activate the ability and have it be effective.