The Stack

[Malleo]

So I have  {Web of Inertia} out and my friend casts two spells, I use  {Stonecloaker} to exile one and then return it to my hand but then he says he exiles the other one in response to me exiling and attacks. Can he do that?

So...lemme get this straight. Your opponent casts 2 spells and they both resolve. So he has 2 cards in the graveyard now. I think that is what the situation is...but here is what I think you are asking:
"Can I exile the card he chooses for {Web of Inertia} so he can't attack?" Short answer: As long as your opponent has a card to exile in his graveyard, he can attack you. Here is what happens in your situation:

{Web of Inertia}'s trigger goes on the stack, at the begining of the first combat phase. The stack looks like this:
1) web's ability
While it is still on the stack, you cast {Stonecloaker}. The stack looks like this:
1) stonecloak (he has not entered the battlefield yet; still waiting to resolve)
2) web's ability
Now stonecloak enters the battlefield, and his 2 etb abilities trigger. The stack looks like this:
1) stonecload ability
2) stonecloak ability
3) web's ability
The first 2 abilities on the stack now reaolve. You exile a card from his graveyard so there is 1 left. You return stonecloaker to your hand with its other ability. The stack now only has the web's ability on it, once again. it looks like this:
1) Web's ability
Now you do not have enough mana to cast stonecloaker again, so the {Web of Inertia} trigger resolves. your opponent exiles the 1 card remaining in his graveyard and attacks you.

Your opponent choosing which card to exile is part of the web of inertia's ability resolving, so once your opponent chooses which card to exile, it is too late to prevent him from attackig. However, you can respond to the web's ability BEFORE the opponent chooses, while it is on the stack and has not resolved yet. You may use this chance to exile as many cards as you can from his graveyard. But if even 1 is left, he can still choose to exile it when the web's ability resolves, and attack you.

Does this answer your question, or did I assume wrong? I was not clear on the situation you described so forgive me.

Actually this is a good answer but I exiled his card as soon as it hit his graveyard

[Malleo]

What happened was I exiled the first card and then he said he started his combat phase and exiled the other card

[scarsabrex]

What happened was I exiled the first card and then he said he started his combat phase and exiled the other card

As long as there is a card left in his graveyard he can exile it at the beggining of his combat in order to attack.

[Malleo]

What happened was I exiled the first card and then he said he started his combat phase and exiled the other card

As long as there is a card left in his graveyard he can exile it at the beggining of his combat in order to attack.

My main question is can he start his combat phase with cards on the stack?

[La_Jungla]

If you cast an instant like {Murder}, does that then result in a stack on the affected creature, making the Murder-card have it's effect first, thus preventing potential creature card-effects to take place? For example if I use Murder on a creature-spell such as {Seller of Songbirds} - will I then prevent that creature from being summoned AND prevent the token from entering the battlefield?

[SheepAtog]

No. You cannot target a creature spell with  {Murder}. Once the  {Seller of Songbirds} enters the battlefield, it's ability triggers and goes onto the stack. You can respond with a kill spell, which will happen before the tokens, but he will still get tokens unless you {Stifle} or  {Trickbind} to stop the {Seller of Songbirds} trigger resolving from the stack.

[La_Jungla]

Got it! Thanks

[Bilygote]

I attack with a {engulfing slagwurm}. The defending player blocks with a {gomazoa}. He then activates the {gomazoa}'s ability in response to the {engulfing slagwurm}'s triggered ability.

How would this play out?

My thoughts were that he'd have to activate the {gomazoa}'s ability in response to him declaring his block.

[Coffee Vampire]

Yur friend would be correct. Blocks are declared, then the slag's trigger goes on the stack. When your opponent gets priority, he or she can activate an ability like the one you mentioned. His ability will still resolve though, after they leave. The creature is gone, so it can't be destroyed; but you still gain the life.

[Malleo]

So my friend plays  {Consuming Aberration} when I have 0 cards in my GY but as soon as its death goes on the stack he plays a spell and makes me mill, does death due to 0 toughness use the stack?

[Coffee Vampire]

No, it does not use the stack. Creatures with 0 toughness are sent to the graveyard as a state-based action. You cannot "respond" to state-based actions. In the same way, you could not "respond" to your life being 0 by casting {Sphinx's Revelation} for 1.

[Stoneco1d869]

How does the stack work with a creature like  {Hatred}? Can I wait to see if the spell gets countered before paying the life?

[Double-O-Scotch]

How does the stack work with a creature like  {Hatred}? Can I wait to see if the spell gets countered before paying the life?

First off, it's not a creature, secondly you must pay the life as you play the spell, as an additional cost, so no you can't wait to see if its countered prior to paying the life.

[Coffee Vampire]

Scotch is right, all costs must be paid prior to casting a spell. This includes additional costs. The wording on {Hatred} might make it seem like you can pay afterwards, but take a look at the oracle text. That will clear things up.

[Stoneco1d869]

Scotch is right, all costs must be paid prior to casting a spell. This includes additional costs. The wording on {Hatred} might make it seem like you can pay afterwards, but take a look at the oracle text. That will clear things up.

Yeah basically because of the wording I was wondering how exactly the spell would play out. Thanks.