abaut Mana Drain and Chalice of the Void

[new sheep]

A. How much mana will I get If I countered :

1. Skeletal Scrying for 2 (2+B)
2. Chalice of the Void for 2 (2+2)

both with Mana Drain

B. Can I Stifle the mana gain from Mana Drain?

C. Will Chalice of the Void (with one counter on it) counter for example Mind Twist (for X+B) or Skeletal Scrying for 2 (2+B) or Baskin Rootowalla if she was played from Madness cost?

[Limbo]

Mana Drain:

At the beginning of your next main phase, add to your mana pool, where X is that spell's converted mana cost.

Converted mana cost

The mana cost of a card is indicated by mana symbols printed on its upper right corner.

The converted mana cost of an object is a number equal to the total amount of mana in its mana cost, regardless of color.

If a cost has an "X" in it, the mana cost equals the amount announced as part of playing the spell or ability while it is on the stack, but if the card in any other zone, X is treated as zero.

Chalice of the void:

Whenever a player plays a spell with converted mana cost equal to the number of charge counters on ~this~, counter that spell.

A triggered ability begins with the word "when," "whenever," or "at."

The answers for your questions with this info become:

A.1: Three mana (1+x=1+2=3)
A.2: Four mana (x+x=2+2=4)

B: The sentence concerning the free mana starts with "at". As it is a triggered ability, you can stifle it.

C: Mind Twisting or scrying for zero will result in a countered card. Twisting or scrying for anything larger then zero will not be countered by a chalice at one. Basking Rootwalla still has a converted mana cost (CMC) of one with the madness cost, so it will be countered. Remember that countered spells still count towards storm count.

Hope this helps,

Leon

Edit: Remember that when the chalice resolves, the 's in the upper right corner will be treated as zero, so a gorilla shaman will be able to destroy it for +{X}+{X}=1+0+0=1 mana.

[Nefarias]

Mana Drain's trigger produces mana, so isn't it a mana ability, and hence no Stifling?

[new sheep]

If a cost has an "X" in it, the mana cost equals the amount announced as part of playing the spell or ability while it is on the stack, but if the card in any other zone, X is treated as zero.

Right now it's clear. Thanx for help

[Jebus]

Mana Drain's trigger produces mana, so isn't it a mana ability, and hence no Stifling?

It is a triggered ability that produces mana, but it is not a mana ability.

In order for a triggered ability to be a mana ability, it must be triggered off a mana ability.

This is not the case with Mana Drain.  It creates a regular triggered ability and this trigger can be Stifled.

[Machinus]

You must stifle the ability right as soon as it triggers during the next main phase?

[Jebus]

You must stifle the ability right as soon as it triggers during the next main phase?

After it triggers, but before it resolves.

Just like any other trigger.