more to cast except during its controller's turn.Defense Grid makes spells cast outside their controller's turn cost three additional mana. A deck planning to resolve an important sequence on its own turn can use that tax to make opposing counterspells and instant-speed removal much harder to deploy.
The effect is symmetrical. Your own spells also cost more during opponents' turns, which makes Grid a poor fit for some control decks that rely on repeated instant-speed interaction. Proactive combo, artifact, or sorcery-focused strategies are better positioned to accept the restriction because they already expect to do most of their work during their own turns.
Additional costs still apply when a spell is cast without paying its mana cost or through another alternative cost. A free counterspell may therefore require the extra three mana under Grid. However, the artifact does not stop activated or triggered abilities, so opponents may still interact through permanents already on the battlefield. Deploy it with a clear follow-up rather than assuming it locks the table out. Opponents can remove it during their own turns at the ordinary cost, and an early Grid may also make it harder for other players to stop a different opponent's plan. Its best use is creating a practical opening for your own important turn while your deck is prepared to operate comfortably under the same timing restriction.
