Protean Hulk + Hedron Crab + Dryad Arbor

[Nizmox]

Could someone explain to me how this combo works?
The part that confuses me is why do the Hedron Crab's abilities trigger when the Hedron Crabs + Dryad Arbors come into play simultaneously. I would have thought the Hedron Crab's need to be in play first to be able to trigger.

Thanks in advance

[Malchar]

The crab doesn't need to be in play ahead of time. It works.

Basically, if a bunch of stuff enters the battlefield at the same time, you pretend that everything is already on the battlefield and then look at each thing individually and see what it would trigger. A similar property holds for things going to the graveyard, in which case you look back and see what would trigger if that permanent were still on the battlefield. For example, Last Laugh would trigger itself when it is put into a graveyard were it not for the specification which excludes it.

[Nizmox]

The crab doesn't need to be in play ahead of time. It works.

Basically, if a bunch of stuff enters the battlefield at the same time, you pretend that everything is already on the battlefield and then look at each thing individually and see what it would trigger. A similar property holds for things going to the graveyard, in which case you look back and see what would trigger if that permanent were still on the battlefield. For example, Last Laugh would trigger itself when it is put into a graveyard were it not for the specification which excludes it.

Thanks. Would you be able to refer me to the comp rules section?

[cdr]

Thanks. Would you be able to refer me to the comp rules section?

603.6a. (http://yawgatog.com/resources/magic-rules/#R6036a) Enters-the-battlefield abilities trigger when a permanent enters the battlefield. These are written, "When [this object] enters the battlefield, . . . " or "Whenever a [type] enters the battlefield, . . ." Each time an event puts one or more permanents onto the battlefield, all permanents on the battlefield (including the newcomers) are checked for any enters-the-battlefield triggers that match the event.

Malchar is close, but not entirely correct on the details. He was probably inferring from my post on the leaves-the-battlefield rule, which is my fault for not explaining clearly enough. Everything will be on the battlefield, so you don't have to "pretend".

Everyone enters the battlefield as one event, then the game asks what currently exists that has triggers that matched that event. The Hedron crabs do, so they trigger.

The difference between ETB and LTB is that ETB looks at what has triggers that match the event after the event, whereas LTB has to look back at what had triggers before the event that match the event.