I've been playing quite a
bit with people who read a card, decide it's amazing, put it in their
deck, then realize after someone explains to them what the card actually
does why the card is a common.
I am making this article to help you understand how your card effects work so that you can understand how those complicated rulings work. I will use generic terminology and follow with specific examples.
Activate Effects (ACT) - Activate effects can only be used in the main phase. Unless stated otherwise, they can be used as many times in one turn as you can pay the cost for the effect.
Example - Sleygal Dagger's counterblast 1, gain 2000 power if you have 4 or more Gold Paladin rear guards. You can activate this effect as many times as you have unflipped damage, so long as you have 4 other Gold Paladin rear guards.
NOTE - Activate effects are instantaneous. This means that all effects resolve immediately.
Example - Dark Lord of the Abyss has a Limit Break effect. The effect is, counterblast 2, Soul Charge 2, Dark Lord of the Abyss gains 1000 power for every card in your soul until the end of this turn. All power increases occur instantaneously, even if you gain more soul later that turn (even using Dark Lord's effect a second time). This means that if you have 8 soul, activate Dark Lord's effect (costs always occur first) then you will gain 10000 for the turn and nothing will change it. Activating the effect again will give you 12000 more, but won't increase the 10000 you already received, which brings Dark Lord to 33000 for the turn.
NOTE - Activate effects may have continuous effects.
Knight of Fury, Agravain is one of the few examples of a card that has an activate ability that is continuous. Agravain, upon megablasting, gains 1000 power for each of your Gold Paladin rear guards. If this effect was not continuous, then Agravain would always have power equal to how how many Rear-guards he had when he activated the megablast. Since it is continuous, any alterations to the amount of Gold Paladins on the field have an instantaneous effect on Agravain's power. Thus, if the Agravain player has 4 rear guards out, Agravain is 14000. If you retire one of his rear guards, he drops to 13000.
When This Unit... Effects - These effects are ruled the same way as Activate effects. They occur the instant the action triggers the effect and each effect only occurs once per trigger. If multiple triggers for the effect occur simultaneously, they all are resolved one at a time.
When a unit enters soul - Cards like Doreen the Thruster get 3000 power every time a unit enters your soul during the main phase. This means that if two cards enter the soul at the same time, it counts as one card entering soul two times and you get the 3000 power twice. Additionally, with this ruling, if you superior ride a new Vanguard on top of your current Vanguard, that counts as a unit entering soul and triggers the power up effect.
When this unit attacks/boosts - This effect occurs the moment you rest a unit for battle and BEFORE the drive check. I will brush on the examples that people typically get confused on.
If you have less cards in your hand - If you attack with Charging Chariot Knight as a vanguard and you have 4 cards to your opponent's 5, even if you drive check and he guards, Charging Chariot Knight still gains 3000 as his effect occurred before the drive check and guarding steps.
If you have 4 or more cards in your hand - This applies to Milk. Her effect is when she boosts, if you have 4 or more cards in hand, she gains 4000. This means that if you have 3 cards and do a drive check to put you at 4 cards in hand, Milk is still only 6000. Amaterasu does gain the 4000, but that is because her effect is continuous, and not when she attacks.
Limit Break - If your Limit Break effect occurs when you attack and you get a heal trigger, usually you retain limit break effects. This is because most limit break effects are "When this unit attacks" or activated abilities, which when paid, last until the end of the turn. The only Limit Break unit that loses its effect mid-battle would be Great Daiyuusha (so far). Keep in mind that after battle effects like Spectral Duke Dragon's cannot be activated if you lose Limit Break during your drive check (and healing is non-optional).
When This Unit Hits - If you have an effect that says this, all you need to keep in mind is that the attack has to be successful and that your drive check has already occurred. I've seen people think that you can rest all of your units with Laurel's effect (which requires the Vanguard to hit) and stand some of those RG's with stands on the drive check. Since you have to rest the units after the drive check, you can't swing with any units other than your Vanguard unless you get Stands on the second drive check.
Continuous effects - Self-explanatory. These are always in effect as long as the condition of the effect is met.
If any specific questions regarding rulings are brought up, I can answer them.
I am making this article to help you understand how your card effects work so that you can understand how those complicated rulings work. I will use generic terminology and follow with specific examples.
Activate Effects (ACT) - Activate effects can only be used in the main phase. Unless stated otherwise, they can be used as many times in one turn as you can pay the cost for the effect.
Example - Sleygal Dagger's counterblast 1, gain 2000 power if you have 4 or more Gold Paladin rear guards. You can activate this effect as many times as you have unflipped damage, so long as you have 4 other Gold Paladin rear guards.
NOTE - Activate effects are instantaneous. This means that all effects resolve immediately.
Example - Dark Lord of the Abyss has a Limit Break effect. The effect is, counterblast 2, Soul Charge 2, Dark Lord of the Abyss gains 1000 power for every card in your soul until the end of this turn. All power increases occur instantaneously, even if you gain more soul later that turn (even using Dark Lord's effect a second time). This means that if you have 8 soul, activate Dark Lord's effect (costs always occur first) then you will gain 10000 for the turn and nothing will change it. Activating the effect again will give you 12000 more, but won't increase the 10000 you already received, which brings Dark Lord to 33000 for the turn.
NOTE - Activate effects may have continuous effects.
Knight of Fury, Agravain is one of the few examples of a card that has an activate ability that is continuous. Agravain, upon megablasting, gains 1000 power for each of your Gold Paladin rear guards. If this effect was not continuous, then Agravain would always have power equal to how how many Rear-guards he had when he activated the megablast. Since it is continuous, any alterations to the amount of Gold Paladins on the field have an instantaneous effect on Agravain's power. Thus, if the Agravain player has 4 rear guards out, Agravain is 14000. If you retire one of his rear guards, he drops to 13000.
When This Unit... Effects - These effects are ruled the same way as Activate effects. They occur the instant the action triggers the effect and each effect only occurs once per trigger. If multiple triggers for the effect occur simultaneously, they all are resolved one at a time.
When a unit enters soul - Cards like Doreen the Thruster get 3000 power every time a unit enters your soul during the main phase. This means that if two cards enter the soul at the same time, it counts as one card entering soul two times and you get the 3000 power twice. Additionally, with this ruling, if you superior ride a new Vanguard on top of your current Vanguard, that counts as a unit entering soul and triggers the power up effect.
When this unit attacks/boosts - This effect occurs the moment you rest a unit for battle and BEFORE the drive check. I will brush on the examples that people typically get confused on.
If you have less cards in your hand - If you attack with Charging Chariot Knight as a vanguard and you have 4 cards to your opponent's 5, even if you drive check and he guards, Charging Chariot Knight still gains 3000 as his effect occurred before the drive check and guarding steps.
If you have 4 or more cards in your hand - This applies to Milk. Her effect is when she boosts, if you have 4 or more cards in hand, she gains 4000. This means that if you have 3 cards and do a drive check to put you at 4 cards in hand, Milk is still only 6000. Amaterasu does gain the 4000, but that is because her effect is continuous, and not when she attacks.
Limit Break - If your Limit Break effect occurs when you attack and you get a heal trigger, usually you retain limit break effects. This is because most limit break effects are "When this unit attacks" or activated abilities, which when paid, last until the end of the turn. The only Limit Break unit that loses its effect mid-battle would be Great Daiyuusha (so far). Keep in mind that after battle effects like Spectral Duke Dragon's cannot be activated if you lose Limit Break during your drive check (and healing is non-optional).
When This Unit Hits - If you have an effect that says this, all you need to keep in mind is that the attack has to be successful and that your drive check has already occurred. I've seen people think that you can rest all of your units with Laurel's effect (which requires the Vanguard to hit) and stand some of those RG's with stands on the drive check. Since you have to rest the units after the drive check, you can't swing with any units other than your Vanguard unless you get Stands on the second drive check.
Continuous effects - Self-explanatory. These are always in effect as long as the condition of the effect is met.
If any specific questions regarding rulings are brought up, I can answer them.