Understanding Random Cards – Siraf, Unstable Form, and Feln Cauldron

Last Updated for: Set 1

While there are not many random effect cards in Eternal, there are a few. The most notable 3 are Knight-Chancellor Siraf, Unstable Form, and Feln Cauldron, as these all pull from pools of other cards for their effect. The remaining random effect cards like Brazen Daredevil, Crown of Possibilities, and Soulfire Drake have fairly straight-forward effect pools, with easy to calculate effects.

In this article, I’ll be discussing both the mechanical interactions and likelihood of various outcomes from these cards.

Knight-Chancellor Siraf

I’m contractually obligated to believe that Siraf is, in fact, BAE.

Knight-Chancellor Siraf is one of the primary win conditions of most decks that include both time and justice. Her activation can summon any unit that has either Time or Justice in it, including multifaction cards including only one of those colors – eg, Elysian (Time + Primal) or Rakano (Justice + Fire) cards. These units will then activate Summon effects when played.

Usually the units spawned by Siraf just end up providing overwhelming value to the Siraf player, and the random element of her ability does not cause significant swings. It tends to only matter in a few cases – getting outlier activations or cards that have positive effect text or Summon effects.

The way that Siraf’s summon and stat doubling work is that the unit is first summoned, applying Powersurge or taking into account abilities like Timekeeper or Vodakhan, and then a static buff for the same amount gets added. For example, a Timekeeper will be a 6/6 if you activate Siraf with 3 time influence, and will become a 7/7 if you play another time influence, and will become a 3/3 if subsequently silenced. If you have Xenan Obelisks in play, your units get +4/+4 per Obelisk. Shimmerpack is doubled before the transform effect occurs, so it makes transformed units into 8/8s, assuming no Obelisks in play.

As Siraf requires exhausting to activate her ability, she can only be activated once per turn and stuns cause her to be unable to activate. This was changed with the Open Beta patch – beforehand, she could activate through stun and as many times per turn as you had the power to spend.

Currently, there are 111 units in the pool of Siraf units, as of Set 0 and Set 1. The average stats of a Siraf activation, after doubling, is roughly 5.5/6, though there is high variance in this number.

  • Flying units: 23 unconditional (20.7%) + Champion of Wisdom and Flight Lieutenant
  • Aegis units: 5 (4.5%)
  • Empower units: 13 (11.7%)
  • Overwhelm units: 8 (7.2%)
  • Summon units: 24 (21.4%)
    • Silence units: 2 (1.8%) + psuedo-silence in Shimmerpack
    • Powersurge units: 1 (.85%) – Beware this if you need to cast things after Siraf activation!
  • Charge units: 2 (1.7%) with a psuedo-Charge in Crownwatch Cavalry providing immediate damage to an existing board.
  • Lifesteal units: 4 (3.6%)
  • Heal units: 3 immediately (2.7%), 1 via Empower, 1 via blocking, 1 via card draw (5.4% total)

About the only effect that can be relied on to pop out of Siraf is a Flying unit, appearing roughly 1 in 5 times. Over 3 activations, there’s about a 50% chance to get at least 1 flying unit.

Of course, certain card text is a bit more “bomby” than others. What you consider a “bomb” result from Siraf will differ, but my count is that about 18 units are what I would consider truly above and beyond the average Siraf activation, in terms of text + stat combo – about a 16% chance. So, while these will crop up, the odds of any single result shifting the game more than a source of free bodies isn’t very high.

There are 3 units that may end up dead after the activation resolves: Timekeeper (this unit will only end up dead if you got Siraf via a transform or steal effect, as Siraf requires a Time influence to be played), Copper Conduit (if you activate Siraf with exactly 8 power, as the Powersurge effect will trigger on activation), and Idol of Destran (who is always dead unless you have a Xenan Obelisk).

Unstable Form

More like Funstable!

Unstable Form (or Funstable Form, as it has been nicknamed) is a unique card with very high risk and the potential for very high reward. Unlike Siraf, Summon effects do not trigger from Unstable Form transformations. It can be used as situational removal, if the text on a card is more important than its body (eg., Sandstorm Titan), or to buff your cards if the majority of their power budget is tied up by Summon effects (eg. the acolyte cycle, Jotun Hurler) or the card can be cheated out below cost (eg. North-Wind Herald or Lurking Sanguar). Other strong offensive uses of Unstable Form include Copper Conduit and False Prince, replacing your opponent’s large minion with a random 1-drop, thanks to the transformation effect of False Prince and the variable cost of Copper Conduit.

The cost of a card is constantly updated, regardless of what zone it’s in, which will affect the result of Unstable Form. If you cast Unstable Form as your second spell in a turn, a targeted North-Wind Herald will turn into a 1-cost unit. Similarly, Unstable Form on a turn 1 Infernus will result in a 1 drop. Also, if a card’s cost is reduced by any effect (eg., a temporary effect like Sauropod Wrangler or a permanent effect like Nesting Avisaur) Unstable Form will use this reduced cost.

Unstable Form will not remove the effect of the spells Madness or Haunting Scream – if you madness a unit then cast Unstable Form on it, it will still return; if you reanimate a unit with Haunting Scream then cast Unstable Form on it, it will still die at the end of turn. Early in Closed Beta, these tricks worked, but were later removed.

If a card is stunned, either temporarily or via Permafrost, transforming it into a unit with Endurance will break the stun and the unit will be ready. Permafrosts will be be broken, and moved to the void.

Like all transformation effects (Polymorph, Shimmerpack, etc), equipment on a unit persists. If an enemy unit is a threat because of equipment, Unstable Form won’t bail you out. However, any buffs that are not from equipment (eg., from Warcry or spells like Righteous Fury) do not persist.

As it is a targeted spell, Unstable Form does break Aegis on units.

The most notable costs for Unstable Form are 7, 8 and 10 cost cards. Many bomb-cards exist at the 7-cost slot and almost all of them have text that puts them above and beyond even a fairly strong average rate for that level of cost. While there are a few exceptions – Mistveil Drake (its Fate and Summon don’t activate), Araktodon, and Shimmerpack – 7-cost units will typically end up as game-enders in draft and even constructed when cheated out.

8 is notable, however, for the opposite reason – most of the 8 cost cards are Scions, and while these may have strong effects, they’re only relevant if you get a Scion in your faction. If you have no Primal spells in your deck, Eilyn is a downgrade compared to many 7 drops. Rolant is the exception, as an invulnerable unit can be a good roadblock, but he’s still a bit weak in comparison to many 7-drops. Snowcrush Animist and Marisen, the Eldest hang out at this cost as well, but without its Summon, the former is just a mediocre body. Marisen, the Eldest is certainly the strongest card at this cost, but with only a 1 in 8 chance to get her, using Unstable on a 7-drop should only be used in desperation.

9-cost is only a single unit, Lavablood Goliath, which is mostly useless without it’s Summon effect. You should avoid raising a unit to 9-cost, unless you have another copy of Unstable Form ready. 10-cost is also only a single unit, but the unit with the strongest ongoing effect in the game: Scourge of Frosthome. While Scourge is in play, its owner’s opponent cannot cast spells, forcing them to rely on Summon effects to hopefully clear Scourge off the board.

I hope you really needed that 11/11

Finally, if you cast Unstable Form on a 10-cost card, it turns into an 11 cost 11/11 Golem and any further casts will increment the cost, power, and health by 1. However, given how strong Scourge of Frosthome is, this is not recommended.

Following is the full chart of average stats for cost 1-8 units, how many units exist at that cost, and the chance of getting a flying unit or endurance unit at any given level:


This can also be found in a Google Spreadsheet.

Feln Cauldron

Your opponent will draw Furnace Mage at 4/5 activations every time.

For those familiar with a certain other digital card game, the idea of a large quantity of redundant spells having a somewhat reliable aggregate effect may not be an alien idea. While any RNG element has variance, how reliably can you expect certain effects from Feln Cauldron? Is there enough redundancy in the Eternal spell-base to get somewhat reliable effects? There are a total 104 spells total in Eternal.

The odds to get at least 1 of any specific effect is as follows:
1 – ((1- X/104) ^ 5)

  • Silence: 3 (2.8% individual, 13.6% to get effect)
  • Attachment destruction: 2 (1.9% individual, 9.2% chance to get effect)
  • Heal: 3 unconditional (2.8% individual, 13.6% to get effect)
  • Counterspell: 2 (1.9% individual, 9.2% chance to get effect)
  • Discard/hand info: 2 full hand, 3 subsets of hand (4.8% individual, 21.8% chance to get effect)
  • Sweeper: 4 (3.8% individual, 17.8% to get effect)
  • Aegis pop (cards that are not sweepers that unconditionally pop aegis on units): 35 (33.3% individually, 87.1% chance to get effect)

Basically, no. The payout of Feln Cauldron is going to end up with extreme variance in the effect you get. You’re almost guaranteed to get a card that can unconditionally target a unit, but this is a very loose category that includes things like casting Righteous Fury as an aegis pop. However – note that at even 5/104 cards, the chance to affect your opponent’s hand in one of the five cards you receive is almost 1 in 4. Depending on the cards that Set 2 adds, Feln Cauldron may end up somewhat reliable in some of these effect categories. Of course, being a random card, it’ll always just give you 5 off-faction Favors instead.


I hope this information helps you all make more informed choices with Siraf, Feln Cauldron, and Unstable Form – I find this card is somewhat underrated in draft and there is still unexplored build-around territory in constructed. And finally, I’d like to thank Jellomoose and his website, Eternaldecks.cards and specifically the card search page for helping me gather the data for this article!

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