Rain of Arrow is a new removal card for Forestcraft that might be suited for a more control playstyle. At a glance, it is reminiscent of the AOE removal cards that used to be staples in Forestcraft, like Aria’s Whirlwind. That iconic card came in handy against wide boards and became stronger as more cards were played at the same turn.
This card also contains a newly introduced keyword: Transmute. It is a very straightforward keyword that simply changes a card into another card after a requirement is fulfilled. In this case, when you fuse 6 or more cards into Rain of Arrows at once, it will transform into Deluge of Arrows, which can deal direct damage to the enemy leader. But be wary that once you Transmute a card, you can no longer use the previous card's effect.
Rain of Arrows is a 3PP card that deals a base 3 AOE damage and up to 6 damage after playing at least two cards beforehand. This effect is quite strong against standard wide boards with its base effect and can handle most decks' turns 5–7 boards with its 6-damage AOE. However, due to its relatively high 3PP cost, it might not be easy to add this card into your deck. From the cost alone, this card definitely isn't suited for an aggressive playstyle.
Midrange or tempo Forestcraft decks are also probably not suited for Rain of Arrows' effect, as most of Forestcraft's payoffs heavily depend on follower count. Paying 3PP for removal without creating a board to increase the follower count is such a big drawback. It’s only justifiable to play this card as a tech, if there is a threat in the meta that can only be cleared efficiently via Rain of Arrows.
The only suitable playstyle to use Rain of Arrows is control: 3PP is a fair cost for AOE removal, and its presence as a spell card means it won’t interfere with specific follower tutoring—which is usually present in control archetypes. It also draws a card if it is used as a combo piece, which is a nice bonus to refill the hand size.
But as we know, Control Forestcraft is currently centered around Ultimate Bahamut — and that archetype will be gone in the next expansion. This means the viability of Rain of Arrows also depends on future control win conditions.
Rain of Arrows accepts every single Forestcraft card as fusion material. Fusion is not only handy as a way to achieve transmutation but also as a way to control your hand size and prevent yourself from overdrawing. In a sense, this effect is pretty similar to Cleaver Cat's, which does see some play in decks that have problems with overdrawing cards.
Deluge of Arrows has an effect that deals damage equal to the number of cards drawn when you play it. As Deluge of Arrows costs 8PP, the most reasonable timing is to transmute it on your turn 8 by fusing every single card in your hand. This will guarantee the maximum 7 damage from its effect.
It is also important to note that playing Neutral cards in your deck will lower the damage consistency of Deluge of Arrows, since Neutral cards are unable to be fused—which results in drawing fewer cards from Deluge’s effect.
Deluge of Arrows is a powerful card that deals 7 damage to enemy leaders while clearing the board. However, 8PP is simply too expensive for that kind of effect: in this metagame, you need to be able to deal 15+ damage within a single turn in those late turns, especially for control or combo decks. A measly 7 damage is simply inferior to the other meta options.
Since Deluge of Arrows is able to draw up to 7 cards, It synergizes well with Carbuncle, Sacred Emerald, which allows you to draw multiple 0-cost cards that can increase your damage output. However, Carbuncle will be rotating next expansion, so this synergy is not relevant for Rotation. Moreover, since Deluge of Arrows should almost always be played on the same turn it is Transmuted, there is simply no window to efficiently play cost-reduction cards.
So, the only viable way to use Deluge of Arrows is to use it in combination with big Ambush followers, such as Cosmos Fang. If you can safely hold Cosmos Fang without evolving on your turn 7, you can pull off an OTK if your opponent decides to play five followers: Fang will deal 13 damage on her own, and the last 7 damage will come from Deluge of Arrows. However, as Deluge works best without Neutral cards in your deck, it could be difficult to build a deck around Cosmos Fang: the card relies on staple Neutral cards, such as Winged Inversion or Asuka & Shiori, Twins.
Other than Cosmos Fang, this card’s viability depends on new card effects in the future—maybe some kind of damage increase, similar to Ravening Corruption's leader effect that benefits from draw, or a Loki effect that doubles the expected damage.
While Deluge of Arrows feels underwhelming as a finisher, I think the base card, Rain of Arrows, does have some potential to be included in a control archetype. A 3-damage AOE without any condition attached is more than enough to answer most early- to midgame boards. And because it’s an AOE card, it can destroy even Ambush followers. Depending on the metagame, it might even be viable as tech for a Midrange Forest archetype.
Overall, I doubt that this card will make a big impact, as it doesn’t look too impressive at the moment. I hope that we will get more support in the future that makes it worth playing this control-oriented card.