Will state triggers cause a draw if their condition is always true?

Question

If I have Hidden Predators and Enchanted Evening on the battlefield, will the game end in a draw as soon as my opponent has a creature with power 4 or greater enter the battlefield?

If I understand the layers correctly, then Hidden Predators will be an Enchantment and a Creature, because even though its own ability normally removes the Enchantment type, the ability of Enchanted Evening will make it stay an Enchantment. This means that every time the state trigger of Hidden Predators resolves, it will immediately trigger again.

Assuming no player has an instant to get rid of any of the 3 cards in question (or to kill their opponent), does this cause an automatic draw?

Edit It turns out I was wrong about the layers. I thought that a continuous effect like "all x are y" would take precedence over a type-setting effect like "y becomes x".

Answer 1

Your example doesn't cause infinite state triggers as murgatroid explains. You controlling Darksteel Reactor with 20 counters while your opponent controls a Platinum Angel would do it however.

In this case yes the game will be a draw as long as there is no way to stop the state trigger. Note that 'no way' in this case only means choosing different options or targets if that is possible, neither player is required to play spells or activate abilities to stop the trigger even if they have the ability.

603.8. Some triggered abilities trigger when a game state (such as a player controlling no permanents of a particular card type) is true, rather than triggering when an event occurs. These abilities trigger as soon as the game state matches the condition. They’ll go onto the stack at the next available opportunity. These are called state triggers. (Note that state triggers aren’t the same as state-based actions.) A state-triggered ability doesn’t trigger again until the ability has resolved, has been countered, or has otherwise left the stack. Then, if the object with the ability is still in the same zone and the game state still matches its trigger condition, the ability will trigger again.

716.4. If a loop contains only mandatory actions, the game is a draw.

716.5. No player can be forced to perform an action that would end a loop other than actions called for by objects involved in the loop.
Example: A player controls Seal of Cleansing, an enchantment that reads, “Sacrifice Seal of Cleansing: Destroy target artifact or enchantment.” A mandatory loop that involves an artifact begins. The player is not forced to sacrifice Seal of Cleansing to destroy the artifact and end the loop.

Answer 2

In general, a state-triggered will trigger repeatedly and draw the game if its trigger condition continues to be true, but the situation you describe does not meet that prerequisite, so the game will not be a draw.

Once the three relevant permanents are on the battlefield, the next time Hidden Predators triggers, it will stop being an enchantment again, and the game will just go on as usual.

Lets say we have the state where Hidden Predators is already a creature, your opponent controls a creature with power 4, and you cast Enchanted Evening. The game plays out like this:

1. Immediately after Enchanted Evening resolves, two relevant continuous effects apply from Hidden Predators and Enchanted Evening respectively:

   • Hidden Predators is a 4/4 Beast Creature.
   • [Hidden Predators] is an enchantment in addition to its other types.

   They are applied in timestamp order, so the result is that Hidden Predators is a 4/4 Beast Enchantment Creature.

2. Now, all of the conditions are met, so Hidden Predators' triggered ability triggers again.

3. Hidden Predators' triggered ability resolves, and we get an additional relevant continuous effect:

   • Hidden Predators is a 4/4 Beast Creature.
   • [Hidden Predators] is an enchantment in addition to its other types.
   • Hidden Predators is a 4/4 Beast Creature.

   Again, these effects are applied in timestamp order, so Hidden Predators is once again just a 4/4 Beast Creature.

After that, Hidden Predators is once again not an Enchantment, so the ability does not trigger.

The rule that governs this interaction is 613.6:

• 613.6. Within a layer or sublayer, determining which order effects are applied in is usually done using a timestamp system. An effect with an earlier timestamp is applied before an effect with a later timestamp.

  • 613.6a A continuous effect generated by a static ability has the same timestamp as the object the static ability is on, or the timestamp of the effect that created the ability, whichever is later.

  • 613.6b A continuous effect generated by the resolution of a spell or ability receives a timestamp at the time it’s created.

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In a different situation, with different state-triggered abilities, those abilities can cause a draw. For example, as diego mentions, if you control a Darksteel Reactor and your opponent controls a Platinum Angel, then the ability just triggers forever in a loop that can't be stopped unless a player can remove one of those permanents at instant speed.