How does me running into OP territory just keep happening?
I don't know, but my guess is that you don't consider (some of) the following factors:
1) how much (virtual) cards is your effect worth compared to the effects of the other characters
2) how might
other people act when being able to use this ability.
3) how would it feel if this effect was used on me
4) how to counter this effect
5) how often is this effect going to be used.
Examples:
1) Suika's passive is the same as a Power card, thus it is worth 1 card.
Patchouli's passive lets her carry 2 - 3 more cards, which is roughly worth half a card per card to carry more, so 1 - 1.5 cards (basing this on intuition, to be fair)
Keine can cycle a card, which is worth 1 card.
Yuuka can draw one card per hit. If we assume that, without Spell Cards, you attack 1.5 times per round (maybe more), and maybe around 66% of these attacks hit, it's worth around 1 card. With her Spell Card... probably more like 2+ cards.
2)
Really, you just have to look at the ability and consider how often and when the ability is used.
Satori can look at another player's hand whenever, once per round. Do you want to use it right before an attack, maybe during your partner's turn and signal them some information, maybe just before your next turn hits so you can get more information every two rounds, etc.
Miko can target anyone with her Spell Card's ability. Another player, or even herself. How many cards does another player need to have in order for its effect to be viable? When would you use it on yourself?
Basically, you need to look at more than just how you would instinctively use it, but also look at other alternatives to make sure you're not overlooking something, like with your latest Koishi. "Dodging one attack for free per round isn't much." It is, when you consider that 2 damage through 2 attacks during one turn is a huge swing and accomplishment in this game.
3)
If I need to pay an extra card to dodge any of Reimu's attacks, how does that feel? Is letting yourself get hit here a viable option rather than losing 2 cards?
Answer: It's viable, as you can use your dodge cards in hand when other people attack you. (If Reimu is the only one targeting you, you may use it against her.)
If a character gets one free attack in one round, what are the implications? You need to spend 2 cards, which is the amount of card draw you get each turn, to simply deal 1 damage. I need a Power or other effect to attack multiple times per round, or I need to use my (rare) Spell Card. If I want to deal 2 damage, I need to use one of my remaining cards in my hand and get a card deficit (you need to use 3 cards while only drawing 2 per turn, thus you are at -1), which is a huge risk (less resources means you are more likely to be attacked as you have less chances of having a dodge card).
Even while Reimu's and your Koishi's effects seem similar at first glance (you need to waste cards in order to accomplish something), with Reimu, you can spend your resources in other places and forego Reimu's extra costs. With your Koishi, if you want her dead, you need to attack her and waste a card, nothing you can do about it. True, these situations also exist with Reimu (her being the only one attacking you, 1v1 situations, ...), but with your Koishi, as soon as you engage in combat with her, you are hit by this effect.
And now, to get back to the original point,
how does it feel?Reimu: Feels a little bad to waste resources, but it feels great if you don't spend your resources against her and you actually can use it somewhere else for a better effect.
Koishi: Feels bad because there's nothing you can do without relying entirely on RNG (having chosen someone with a Last World Spell Card or getting Last World from the center deck to negate her free dodging for an actual attack... or maybe Last Shot/ Remilia's Spear work, since you cannot dodge them. But again, requires 100% RNG and no strategy/ planning).
4)
I pretty much wrote about this in 3 already. What do you need to counter the effect?
Suika's passive: Get a Focus. Or just ignore it, as +1 Range +1 Attack per Turn isn't that troublesome, as it requires Suika to have the resources to begin with.
Reimu's passive: spend your dodge cards elsewhere and tank the hit as long as you have enough live. Doesn't always work, but it's a viable strategy.
Koishi's passive: requires a few select characters that you have to get at the start of the game or one of two one-of-a-kind cards from the center deck. Far too unreliable to be a strategy.
And reliability of a counter is the key for this point. If it's unreliable, then your effect is too powerful.
5)
Generally not a problem to you, since your effects tend to be too strong, and this case is most useful for underpowered effects, but I felt like listing it for completeness' sake.
Please note that this is only for active skills, not for passive buffs and effects that automatically trigger.
There's three general possibilities here:
a) never/ rarely: The effect is entirely useless or there are better alternatives most of the time. (Nitori's second passive ability. If she didn't have a distance buff, her passive would be the worst in the entire game IMO). This can be used to giev a powerful character a little something more, without making them too powerful (e.g. if they otherwise seem bland), or to balance a strong Spell Card with a rarely used passive.
b) situational/ regularly: The effect is used a good chunk of the time, (Utsuho's passive. You don't want to discard two cards every turn, but if you REALLY want to finish someone off but don't have an Invocation, this will save your butt.)
c) always/ whenever possible: If you land here, you've either made a really good effect (that might be on the verge of being too powerful), or an entirely broken one. (Most of your Spell Cards. Yes, they are supposed to be powerful, but only in the right situation. Most of yours can be spammed whenever and be incredibly good. Best example: your Komachi that puts one character into range of everybody else.)
There's probably some more points to consider, but it's 9:30AM at the point of writing this, and I haven't slept yet.
Either way, these 5 points should be the most important that you should always consider when making a new effect.
Character Card
The Closed Eyes of Love
Koishi Komeiji
Passive
Koishi has +1 Distance.
Spellcard - Action
Dream Sign "Ancestors are Watching You"
You may discard up to 2 cards when you play this card.
Attack a player in range. For each card you have discarded, you may attack that player again.
That seems fair enough, I think.
Discarding two cards means you will be, assuming you start out with 6 cards and attack once, left with 2 cards, which means you're likely to be attacked for being out of resources. Being hit then will generate a card. However, not actually being hit due to your spell will (sort of) generate a virtual card (in this circumstance) (which is the Danmaku card used to attack you later on).
In other words: being hit is worth 2 cards (the Danmaku card used by your opponent and the card you draw for losing 1 life)
Thus, in the end, this effect is about as powerful as Utsuho's Spell Card, as she loses 1 life to attack 3 times. And as stated above, 2 cards roughly equal 1 life.
Although my math may be WAY off here. But that's how I look at it.
...I'm going to take your word for it, because I honestly don't understand the true value of range boosting. I think that I've grown incredibly rusty in terms of Danmaku!!(I honestly want to play more Danmaku!! on TTS so that I can actually hone my senses for this sort of thing...)...
+1 Range: Really important so you can engage in combat with players who might not be able to counterattack.
+2 Range: Really good as Focused character next to you and all regular players can now be hit (unless it's an 8 player game).
+3 Range: Amazing. You can hit anyone you want under most circumstances.
+4 Range and higher: Range has lost all meaning beyond this point. You can equip more Powers to protect the ones you already have, but that's about it. Even the attacks per turn are kind of irrelevant if you have 4 of them, as you usually don't have the resources to attack that often, anyway. Really, the only reason to stack so much Range is to either get the "I have all the Powers!" achievement, or to attack Byakuren despite self-buff.
That's how I basically handle Range.
Same goes for Distance.
Character Card
Petty Patrol Tengu
Momiji Inubashiri
Passive
Momiji can have 2 Defense cards in play at the same time.
Spellcard - Reaction
Mountain Nomad "Expellee's Cannan"
Activate either when another player attacks or any time you can play an Action card.
You may choose to cancel the attack, if any, and you may attack a player, regardless of range.
It seems okay now (I don't know how powerful the possibility of equipping two items really is, but in the sketching stage, this seems fine to me), and while her Spell Card is perfectly fine, it does still not seem special enough to warrant being playable whenever you want. I'd just give her a static Reaction Spell that lets her cancel a Spell, since otherwise, if you use your Spell Card during your own turn, it literally just transforms into another attack (that can ignore distance, but still.)
This "activate during your own turn" portion actually falls under case 5's rarely used category.
*remembers that Miko's spellcard is effectively a single target Tempest*
*remembers that Futo's spellcard switches the hands of two different players*
It's true that I've completely forgotten about these effects. However, I was mostly talking about passive abilities earlier. Bad excuse aside, personally, there's actually another interesting point to this:
Miko and Futo both give you other cards in return and never leave you with an empty hand... except if Futo makes you switch hands with a player who has no cards left.
And to be honest, even if these two Spell Cards are in the game, that doesn't mean I like them.
That, and most of the time, Miko uses her own Spell Card on herself to gain 3 cards while she has an empty hand.
And Futo's Spell Card is terrible for herself and only works when she has/ is a Partner. And even then, if her Partner has more/ better cards than anybody else on the board, her Spell Card is weak, which is why Futo rarely saw play in our group.
And regarding Yukari, she can steal one Item/ hand card when she uses her Spell Card. Since it's only one, I suppose it's all right? Considering it's a Spell Card we're talking about here. I mean, getting one card stolen is pretty mean, but there's a lot more powerful effects, which is why this seems fairly tame by comparison.
That, and Spell Cards are (fairly) rare, so this stealing mechanic won't be overused here.
Character Card
Ghost Girl in the Netherworld Tower
Yuyuko Saigyouji
Passive
When a player is hit with Yuyuko's attack, instead of discarding a Powerup card, you may choose to force that player to trash one card at random from their hand.
Spellcard
Lifespan "Ticket to the Ageless Land"
Choose a target in range. That target loses one life. (This is not considered an attack.)
---
Given that a player gains a card whenever they lose life for any reason(unless I'm remembering the rules wrong), the passive isn't really that strong(although I have time and again been proven wrong), and it comes at the cost of letting the player you hit keep their Powerup cards. Also, Yuyuko's spellcard doesn't synergize with her passive at all, as it's not an attack, so it doesn't cause anything other than a loss of life(no Powerup discard if it's not a hit from an attack, if I'm remembering the current set of rules correctly), and the targeted player can draw a card for losing a life, so it's sort of generating a card disadvantage as a cost for being an "undodgeable life loss" sort of thing, and it respects range, unlike Remilia's spear.
After reading your thought process on this, I have to agree, this does seem okay.
Not as powerful as official Yuyuko (I think), but definitely not weak.
That said, i still want to see official Yuyuko in action to see her actual power for myself (as the more I look at her, and especially the older cards, she seems to be getting tamer each time. xD; )