As for unmentioned cards: Runechanter's Pike can be a very powerful effect for very little mana (it's also a nice way to get some variety in your equipment).
Chandra's Spitfire, as mentioned above, is often criminally underrated. In many ways it's an improvement over Pyromancer's Swath (more vulnerable, but can be precast and gives an additional 3 damage instead of 2). Have it out with Gelectrode or Guttersnipe and every Ponder means 4 or 5 damage (in addition to the 5 already threatened). One of my best plays in cube involved no plays turn 1 or 2, a Chandra's Spitfire on turn 3, and then a turn 4 kill with Grapeshot pumping Spitfire immensely.
I don't know about Nivmagus Elemental. I have him in, but he hasn't seen any play yet. I think only storm and replicate are really going to make him worthwhile, but he does have a strong upside.
EDIT:
Also, Flame Jab and Shrine of Burning Rage are fantastic. Maybe Shrine of Piercing Vision could be good as well?
A bit about other colors.
I really wanted another color to help this deck out. I've been experimenting with green for Quirion Dryad, Search for Tommorrow, Rampant Growth, Nimble Mongoose, and Werebear. I want there to be more, but I haven't really found it (Call of the Herd / Beast Attack / other token makers?).
Black is also a candidate, for Yawg Will, Toshiro Umezawa, and Nightscape Familiar.
Intimidator Initiate is not good enough.
The way I've been building this in my cube is for it to blend with red aggro/burn (Kiln Fiend, Shrine of Burning Rage, Chandra's Spitfire, Guttersnipe, burn spells), Storm (Rituals, Card Draw, Ramp, Grapeshot), and other useful tools for tempo and control generally (cantrips, cheap spells). Since most of the cards in the deck legitimately belong in other decks, there is relatively little dedicated support that needs to be run. Delver, Nivmagus Elemental (if it lasts), and Runechanter's Pike are probably the most dedicated--everything else works well in other decks.
Not it doesn't. Soulbond still uses the stack (which means that your opponent can kill the Navigator before they are bound together).
So what? Consecrated Sphinx (and to a lesser extent Frost Titan, though it costs 2 extra and there's still a tapped permanent) have the same vulnerability. If you're going to tell me that a card is worse than its rivals, please use a metric along which the cards differ.
In what games are you in a bad position if you untap with a 6 drop and another 5-8 drop?
You noticed that not all the creatures he listed were 6-drops? Flickerwisp, Bone Shredder, Blade Splicer, Nekrataal, Huntmaster of the Fells, Azorius Arrester... all these can be cast and flickered (sometimes twice) the turn after the Navigator hits. They also help you to get to the point of the game where you can cast Navigator. Casting Avalanche Riders and flickering them is pretty darn good--and then do it again in response to the echo. Mystic Snake is perhaps even more ridiculous. As for cards he didn't mention: Lone Missionary, Snapcaster Mage, Augur of Bolas, Man-o'-War, Aether Adept, Vendilion Clique, Solemn Simulacrum... the list goes on.
I think the card is very interactive and leads to interesting plays and deckbuilding decisions. I'm playing him.
Reaper -- don't let the hive mind get you down. I've run him from time to time and he's been serviceable in aggressive black, though only in that deck and I run a bit of a downpowered list.
--Sacrifice outlets are typically more valuable than folks give credit for. Any early bunch of tokens can make him scary (e.g. turn 2 Mogg War Marshal or turn 3 Sprouting Thrinax), leading to a large monster very early.
-- In using him as a sacrifice outlet to kill your opponent's creatures, he's fantastic with Living Death (he can also sacrifice himself), Grave Pact, Balance, and Urborg Justice.
-- As for eking out advantage with cards like Hellspark Elemental and Keldon Marauders, there are also cards like Bone Shredder (paying echo is for losers), as well as in response to removal on other creatures you control.
-- His synergy with Bloodghast, Gravecrawler, and Blood Artist are obvious; there is also Reassembling Skeleton in the late game. Finally, he can grow very quickly out of Red point/sweeper range, and the instant nature of the effect can make him difficult for red decks to kill.
The above mention of him as a weaker Greater Gargadon is apt. He's not gigantic like the Garg, but he is an oft-underestimated threat that can get very scary very quickly.
The knight is one of my favorite cards ever printed, especially for cube:
-- It's a solid but not uncuttable card if you don't draft around it.
-- It's a build-around-me, and only becomes truly strong when you draft cards that combine well with it (utility lands, crucible, etc.)
-- It provides a lot of options for players, as it can be used to ramp, or simply sit back and grow itself / remove lands, or fetch utility lands
-- It rewards skilled play
It leads people to draft and play more intelligently, which is the #1 goal of my cube--a fun, balanced draft environment that rewards draftskill and playskill (and improves both). One day in the future, when every card is both a utility cog and a build-around-me, Cube will be perfect. I wish every card were like Knight (and Snapcaster, and Fauna Shaman, and Liliana of the Veil, etc.)
As for Sigarda, I can't think of a less interesting or rewarding card. She's powerful, but--like Jace3--in the most boring possible way.
There are a lot of uses for this card:
1. As incremental gain in aggressive decks--get an extra damage out of your Hellspark Elemental, Keldon Marauders, or in response to removal--a la Greater Gargadon.
2. Trade your bad creatures for their good creatures--like Vendilion Clique, Snapcaster, Flickerwisp, etc.--to improve your attacks (especially good in a token-heavy strategy, where you might start taking out 2-toughness creatures)
3. As a finisher to get the last few points through a wall of blockers or Moat.
4. As a sacrifice outlet (Balance, Viridian Emissary, Yavimaya Elder, Living Death, Zealous Conscripts, Kiki-Jiki, Mimic Vat, etc. etc.)
The card is a useful cog in some decks and a build-around=me in others. Exactly the utility and versatility that cube cards require.
Arc lightning is a powerful effect. It usually costs 3; Skirk Volcanist provides that effect on a 3-power stick for the same price (in addition to losing a couple of mountains). Losing mountains is not ideal, but it doesn't cost "mana" per se. The fact that it can only hit creature, I feel, is its major downside. This card is not Fireblast, but it's good for similar reasons.
I've been running this guy for a bit, and he can lead to some pretty explosive surprises. Two perfectly good creatures can be eliminated at instant speed while tapped out, often allowing for an alpha strike. Plus he swings for 3, which is no slouch.
Lastly, I should point out that most cubes need more morphs if designers actually want to make people guess about what those morphs are, and this is a fine one.
1
(Hint: give them something big)
1
The truth is that the majority of red and blue cheap spells (especially cantrips) go very well in the archetype. It's one reason I run Ponder, Brainstorm, Preordain, Serum Visions, Thought Scour, and Sleight of Hand as one-mana blue cantrips in my ~600. Of course, they're also good in most other blue decks. Of course, Snapcaster Mage is fantastic in the archetype (as he always is in UR), as are Augur of Bolas and Kiln Fiend and Guttersnipe and Talrand.
As for unmentioned cards:
Runechanter's Pike can be a very powerful effect for very little mana (it's also a nice way to get some variety in your equipment).
As mentioned above, Gelectrode is a house.
Chandra's Spitfire, as mentioned above, is often criminally underrated. In many ways it's an improvement over Pyromancer's Swath (more vulnerable, but can be precast and gives an additional 3 damage instead of 2). Have it out with Gelectrode or Guttersnipe and every Ponder means 4 or 5 damage (in addition to the 5 already threatened). One of my best plays in cube involved no plays turn 1 or 2, a Chandra's Spitfire on turn 3, and then a turn 4 kill with Grapeshot pumping Spitfire immensely.
I don't know about Nivmagus Elemental. I have him in, but he hasn't seen any play yet. I think only storm and replicate are really going to make him worthwhile, but he does have a strong upside.
EDIT:
Also, Flame Jab and Shrine of Burning Rage are fantastic. Maybe Shrine of Piercing Vision could be good as well?
A bit about other colors.
I really wanted another color to help this deck out. I've been experimenting with green for Quirion Dryad, Search for Tommorrow, Rampant Growth, Nimble Mongoose, and Werebear. I want there to be more, but I haven't really found it (Call of the Herd / Beast Attack / other token makers?).
Black is also a candidate, for Yawg Will, Toshiro Umezawa, and Nightscape Familiar.
Intimidator Initiate is not good enough.
The way I've been building this in my cube is for it to blend with red aggro/burn (Kiln Fiend, Shrine of Burning Rage, Chandra's Spitfire, Guttersnipe, burn spells), Storm (Rituals, Card Draw, Ramp, Grapeshot), and other useful tools for tempo and control generally (cantrips, cheap spells). Since most of the cards in the deck legitimately belong in other decks, there is relatively little dedicated support that needs to be run. Delver, Nivmagus Elemental (if it lasts), and Runechanter's Pike are probably the most dedicated--everything else works well in other decks.
1
So what? Consecrated Sphinx (and to a lesser extent Frost Titan, though it costs 2 extra and there's still a tapped permanent) have the same vulnerability. If you're going to tell me that a card is worse than its rivals, please use a metric along which the cards differ.
You noticed that not all the creatures he listed were 6-drops? Flickerwisp, Bone Shredder, Blade Splicer, Nekrataal, Huntmaster of the Fells, Azorius Arrester... all these can be cast and flickered (sometimes twice) the turn after the Navigator hits. They also help you to get to the point of the game where you can cast Navigator. Casting Avalanche Riders and flickering them is pretty darn good--and then do it again in response to the echo. Mystic Snake is perhaps even more ridiculous. As for cards he didn't mention: Lone Missionary, Snapcaster Mage, Augur of Bolas, Man-o'-War, Aether Adept, Vendilion Clique, Solemn Simulacrum... the list goes on.
I think the card is very interactive and leads to interesting plays and deckbuilding decisions. I'm playing him.
2
--Sacrifice outlets are typically more valuable than folks give credit for. Any early bunch of tokens can make him scary (e.g. turn 2 Mogg War Marshal or turn 3 Sprouting Thrinax), leading to a large monster very early.
-- In using him as a sacrifice outlet to kill your opponent's creatures, he's fantastic with Living Death (he can also sacrifice himself), Grave Pact, Balance, and Urborg Justice.
-- As for eking out advantage with cards like Hellspark Elemental and Keldon Marauders, there are also cards like Bone Shredder (paying echo is for losers), as well as in response to removal on other creatures you control.
-- His synergy with Bloodghast, Gravecrawler, and Blood Artist are obvious; there is also Reassembling Skeleton in the late game. Finally, he can grow very quickly out of Red point/sweeper range, and the instant nature of the effect can make him difficult for red decks to kill.
The above mention of him as a weaker Greater Gargadon is apt. He's not gigantic like the Garg, but he is an oft-underestimated threat that can get very scary very quickly.
1
-- It's a solid but not uncuttable card if you don't draft around it.
-- It's a build-around-me, and only becomes truly strong when you draft cards that combine well with it (utility lands, crucible, etc.)
-- It provides a lot of options for players, as it can be used to ramp, or simply sit back and grow itself / remove lands, or fetch utility lands
-- It rewards skilled play
It leads people to draft and play more intelligently, which is the #1 goal of my cube--a fun, balanced draft environment that rewards draftskill and playskill (and improves both). One day in the future, when every card is both a utility cog and a build-around-me, Cube will be perfect. I wish every card were like Knight (and Snapcaster, and Fauna Shaman, and Liliana of the Veil, etc.)
As for Sigarda, I can't think of a less interesting or rewarding card. She's powerful, but--like Jace3--in the most boring possible way.
1
There are a lot of uses for this card:
1. As incremental gain in aggressive decks--get an extra damage out of your Hellspark Elemental, Keldon Marauders, or in response to removal--a la Greater Gargadon.
2. Trade your bad creatures for their good creatures--like Vendilion Clique, Snapcaster, Flickerwisp, etc.--to improve your attacks (especially good in a token-heavy strategy, where you might start taking out 2-toughness creatures)
3. As a finisher to get the last few points through a wall of blockers or Moat.
4. As a sacrifice outlet (Balance, Viridian Emissary, Yavimaya Elder, Living Death, Zealous Conscripts, Kiki-Jiki, Mimic Vat, etc. etc.)
The card is a useful cog in some decks and a build-around=me in others. Exactly the utility and versatility that cube cards require.
1
Arc lightning is a powerful effect. It usually costs 3; Skirk Volcanist provides that effect on a 3-power stick for the same price (in addition to losing a couple of mountains). Losing mountains is not ideal, but it doesn't cost "mana" per se. The fact that it can only hit creature, I feel, is its major downside. This card is not Fireblast, but it's good for similar reasons.
I've been running this guy for a bit, and he can lead to some pretty explosive surprises. Two perfectly good creatures can be eliminated at instant speed while tapped out, often allowing for an alpha strike. Plus he swings for 3, which is no slouch.
Lastly, I should point out that most cubes need more morphs if designers actually want to make people guess about what those morphs are, and this is a fine one.
1