Why didn't people realize this?

[Ultima66]

If you have an Oathsworn Giant and Glare of Subdual, you can swing with all and then during the declare blockers step tap all of your opponents creatures (you'll still have an untapped army thanks to the Vigilance) so all of your attacks get through. Hey, what colors alpha-strike better than W/G?

[Æther Reaper]

People do realize that, but Oathsworn is kinda costly. Its better to use serra's blessing. While sacrificing the toughness boost, you do get the trick up and running sooner.

[Mad Mat]

That doesn't work, you can't play spells or abilities between the declare attackers and blockers step(unless maybe if it's really stated on the card, you never know with those old cards)

[Æther Reaper]

It does work. They declare blockers. You tap your attackers to tap the blockers. They can no longer block due to being tapped. This is what stops a provoker from killing something like a wellwisher.

Glare of Subdual was printed in Ravnica by the way. It is not an "old" card.

[GRUNT]

I thought tapping them after they're declared would just prevent them from doing damage, not actually preventing them from blocking?

[Æther Reaper]

If a creature is declared a blocker and then tapped, it is removed from blocking.

[Mad Mat]

You can't play spells between the declare attackers and declare blockers step. I don't know for sure if tapping creatures in the spell step stops the blocking. I doubt it though.

[Æther Reaper]

You can play spells and abilities during declare attacks and during declare blockers, but not between. Subdual is activated during declare blockers, meaning the blockers that are announced are immediately tapped, removing them from blocking.

[Aneximines]

Tapping a creature no longer interferes with its combat damage. Hasn't since 6th edition.

The time to use Glare of Subdual defensively is the moment your opponent's attack phase begins, just before he declares attackers.

First you tap his creatures, then he delcares attackers; he can't declare the ones you've tapped as attackers, but he can choose all, some, or none of his untapped creatures as attackers. If you can tap all of his creatures, he won't be able to declare any attackers.

If you use the Glare to tap a creature that has already been declared an attacker, it will not remove the creature from combat or effect its combat damage.

The time to use Glare of Subdual offensively is just after you've declared attackers. You won't be able to tap your attackers for the Glare because they're already tapped - unless they have vigilance. This way you tap his creatures, and then he declares blockers; he can't block with the tapped creatures, and if you tap all of his creatures, he can't block at all.

If you use the Glare to tap a creature that has already been declared a blocker, it will not not remove the creature from combat or effect its combat damage.

Here's a breakdown of the combat phase:

1. Beginning of Combat step
This happens after the active player's first main phase, just after both players passed over an empty stack (no one had anything more they wanted to do).
The combat step begins, and any abilities that trigger "at the beginning of combat" will go on the stack.
Then players get a chance to play instants and abilities.
This is the last chance for a defending player to tap his opponent's creatures to prevent them from attacking.

2. Declare Attackers step
The active player announces which of his creatures will be attacking (he can only choose untapped creatures that have haste or have been in play under his controll since the beginning of his turn). Those creatures then becomes tapped (except for those with vigilance).
Then abilities that trigger off of creatures attacking trigger and go on the stack.
Then players get a chance to play instants and abilities.
This is the last chance for an attacking player to tap his opponent's creatures to prevent them from blocking.

3. Declare Blockers step
The defending player announces which of his untapped creatures will be blocking, and which creature each of them will block (many abilities, like flying and protection, modify how he can make these decisions).
Abilities that trigger off of creatures blocking or being blocked trigger and go on the stack.
Then players get a chance to play instants and abilities.
This is the time for the attacking player to pump up unblocked creatures so they'll deal more damage to the defending player.

4. Combat Damage step
Comat damage is assigned.
- Unblocked creatures assign damage equal to their power to the defending player.
- Blocked creatures assign damage equal to their power to the creatures blocking them, divided as the attacking player sees fit (some abilities, like trample and banding, can modify this).
- Blocking creatures assign damage equal to their power to the creature they're blocking. If a blocker is somehow blocking more than one creature (this would require a spell or ability), it divides its damage among those creatures as the defending player sees fit (banding can modify this).
All of this combat damage goes on the stack as a single object.
Then players get a chance to play instants and abilities.
This is a good time to play regeneration and damage prevention effects.

5. End of Combat step
Abilities that trigger "at end of combat" go on the stack.
Then players get a chance to play instants and abilities.
This is the last chance in the turn to play spells/abilities that can only be played "during combat."
Then, once everything has resolved, all creatures are removed from combat (they are no long "attacking creatures" or "blocking creatures"), and effects that last "until end of combat" end.
Once the combat phase ends the active player's postcombat main phase begins.


They declare blockers. You tap your attackers to tap the blockers. They can no longer block due to being tapped. This is what stops a provoker from killing something like a wellwisher..

(Tapping a creature that's already blocking does not remove it from combat or stop it from dealing combat damage.)

The idea with the Wellwisher is to tap the Wellwisher after the provoker's triggered ability resolves and untaps it but before you have to declare blockers. That way you will be unable to declare the Wellwisher as a blocker, since it will be tapped.

[Ultima66]

The important thing is that it works.

[Einsteinmonkey]

Aneximines is completely correct.