Begginer question about lifelink and Evra

Question

I have Evra, Halcyon Witness on my deck, she has lifelink and I know that I gain hp from the amount of damage she deals.

Generalizing lifelink I have 3 simple yes or no questions:

• If I attack with her and the opponent blocks me does she give me hp for the amount of damage she deals to that creature?
• If the opponent attacks and I block with her, is the damage she deals returned to me as hp even if she is blocking?
• Do creatures with lifelink only transform damage dealt into hp gain when they only attack the opponent?

And 1 about Evra?

• If I activate the ability to exchange my hp for her power and i get countered with an instant giving -4/0, like "Befuddle" does, does the exchange still happen and I instantly die?

Answer 1

Lifelink on a creature causes you to gain life whenever that creature deals damage in any way. In combat, unblocked creatures deal damage to the defending player, and blocking creatures and blocked creatures deal damage to each other. So if Evra is in any of those situations then it will deal damage and you will gain that much life. One common exception is if Evra blocks or becomes blocked, then the other creature is removed from combat before the damage is dealt. Then Evra will have nothing to deal damage to, so it won't deal any damage and you won't gain any life.

Regarding Evra's other ability, you are correct that if Evra's power somehow becomes 0 before the ability resolves, the ability will make your life total 0 and you will lose.

Answer 2

A creature with lifelink gains you life whenever it deals damage (usually in combat, but sometimes when a card says it fights another creature). Combat damage happens during combat whether the lifelink creature is attacking or bloking (assuming first strike or double strike is not on any of the involved creatures).

Also, in Magic the Gathering it's called Life Total not hp.

Therefore:

If i atack with her and opp block me does she give me hp for the ammount of damage she deals to that creature?

Yes. She deals all of her damage and you gain 4 life.

Opp atacks and i block with her, The damage she deals is returned to me as hp even if she is blocking?

Yes. She deals all of her damage and you gain 4 life.

Creatures with lifelink only transform damage dealt into hp gain when they only atack the opp(opponent)

No. You gain life whenever damage is dealt regardless of combat (attacking or blocking) or fighting.