Cheapest priced copy (Starter Commander Decks): $0.49 at Card Kingdom, near mint, their price list as of .
Tectonic Giant 
Creature — Elemental Giant · 3/4 · Rare · Theros Beyond Death · #158
Whenever this creature attacks or becomes the target of a spell an opponent controls, choose one —
• This creature deals 3 damage to each opponent.
• Exile the top two cards of your library. Choose one of them. Until the end of your next turn, you may play that card.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
8 printings · $0.49 to $4.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Forgotten Realms Commander | 144 | Rare | $0.59 | — |
| Commander Legends: Battle for Baldur's Gate | 808 | Rare | $0.59 | — |
| Duskmourn: House of Horror Commander | 168 | Rare | $0.59 | — |
| Theros Beyond Death Promos | 158p | Rare | $1.49 | $2.49 |
| Theros Beyond Death Promos | 158s | Rare | — | $2.29 |
| Starter Commander Decks | 161 | Rare | $0.49 | — |
| Theros Beyond Death | 158 | Rare | $0.69 | $0.79 |
| Theros Beyond Death | 323 | Rare | $1.29 | $4.49 |
7 rulings from Wizards of the Coast
- 24 January 2020Tectonic Giant doesn't change when you can play the exiled card. For example, if you exile a sorcery card, you can cast it only during your main phase when the stack is empty. If you exile a land card, you can play it only during your main phase and only if you have an available land play remaining.
- 24 January 2020Playing an exiled card causes it to leave exile. You can't play it multiple times.
- 24 January 2020An ability that triggers when a creature becomes the target of a spell resolves before the spell that caused it to trigger. It resolves even if that spell is countered.
- 24 January 2020If you don't play the exiled card that you chose, it remains in exile with the card you didn't choose.
- 24 January 2020Players can cast spells and activate abilities after the triggered ability resolves but before the spell that caused it to trigger does.
- 24 January 2020If a spell targets Tectonic Giant more than once, its ability triggers only once.
- 24 January 2020You choose which of the exiled cards you'll be able to play while the ability is resolving. You can't wait to pick one later. The other card remains in exile.