Just to get the conversation going, here is a basic build that I use for my favorite blaster. Its shown with SO's and a couple of specialty IO's. I use them because, generally, when a character hits 22 I buy and use level 25 generic IO's until 40th level or so before I start worrying about sets and stuff.
Don't overlook Shiver's potency against large groups of foes, just because orange or green numbers dont appear overhead doesn't mean you're not maing a difference. Through early levels, hover + chillblain is a potent way to hunt solo higher level bosses in areas like Steel and Skyway. When you're out of melee range foes have to use generally weaker ranged attacks, and those are slowed dramatically by chillblain's secondary effect.
Hero Plan by Mids' Hero Designer 1.803
http://www.cohplanner.com/
Click this DataLink to open the build!
Level 50 Mutation Blaster
Primary Power Set: Fire Blast
Secondary Power Set: Ice Manipulation
Power Pool: Flight
Power Pool: Fitness
Power Pool: Speed
Ancillary Pool: Flame Mastery
Hero Profile:
Level 1: Flares -- Acc(A), Acc(3), Dmg(7), Dmg(13), Dmg(31), Decim-Build%(43)
Level 1: Chilblain -- Acc(A), Acc(36), Dmg(37), Dmg(37), Dmg(37)
Level 2: Fire Blast -- Acc(A), Acc(3), Dmg(7), Dmg(13), Dmg(31), RechRdx(31)
Level 4: Fire Ball -- Acc(A), Acc(5), Dmg(5), Dmg(11), Dmg(15), RechRdx(15)
Level 6: Hover -- EndRdx(A)
Level 8: Fire Breath -- Acc(A), Dmg(9), Dmg(9), Dmg(11), RechRdx(27)
Level 10: Swift -- Flight(A)
Level 12: Hurdle -- Jump(A)
Level 14: Aim -- RechRdx(A), RechRdx(17)
Level 16: Build Up -- RechRdx(A), RechRdx(17)
Level 18: Blaze -- Acc(A), Acc(19), RechRdx(19), Dmg(23), Dmg(25), Dmg(25)
Level 20: Stamina -- EndMod(A), EndMod(21), EndMod(21), P'Shift-End%(40)
Level 22: Ice Patch -- RechRdx(A), RechRdx(23)
Level 24: Fly -- Flight(A)
Level 26: Chilling Embrace -- EndRdx(A), EndRdx(27)
Level 28: Shiver -- Acc(A), Acc(29), Range(29)
Level 30: Rain of Fire -- RechRdx(A), RechRdx(34), Dmg(46), Dmg(46), Dmg(46)
Level 32: Inferno -- Acc(A), Dmg(33), Dmg(33), Dmg(33), RechRdx(34), RechRdx(34)
Level 35: Hasten -- RechRdx(A), RechRdx(36), RechRdx(36)
Level 38: Freezing Touch -- Acc(A), Acc(39), Hold(39), Hold(39), Hold(40), RechRdx(40)
Level 41: Char -- Acc(A), Acc(42), Hold(42), Hold(42), Hold(43), RechRdx(43)
Level 44: Fire Shield -- EndRdx(A), ResDam(45), ResDam(45), ResDam(45)
Level 47: Rise of the Phoenix -- RechRdx(A), Dmg(48), Dmg(48), Dmg(48)
Level 49: Melt Armor -- Acc(A), Acc(50), RechRdx(50), RechRdx(50)
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Level 1: Brawl -- Empty(A)
Level 1: Sprint -- Empty(A)
Level 2: Rest -- Empty(A)
Level 1: Defiance
Level 6: Ninja Run
I'll just add.
Ice patch is great, and lets you get more use out of Rain of Fire. pre level 20.
That said...
Shiver is the defining power that will keep you alive! Once I added that to my build bosses became a joke.
Oh, and since your Fire/ might wanna avoid Frozen Aura? Frozen Shards?...Frozen touch...
Whatever the tier 9 is, it's junk when your Fire/. It's an AOE sleep, and since you'll be packing quite a few damage AOE's...
Otherwise enjoy! I'm a blaster at heart, always have been and this is by far my favorite combo. 
Maestro Mavius - Infinity
Capt. Biohazrd - PCSAR
Talsor Tech - Talsorian Guard
Keep Calm & Chive On!
Fire/Ice is a fun and very solid Blaster combination. I threw something together, that should be very safe (softcapped range with a small purple, PFF+Aid Self+FoN) while still being able to dish out pain on a large scale.
Hero Plan by Mids' Hero Designer 1,803
http://www.cohplanner.com/
Click this DataLink to open the build!
Level 50 Technology Blaster
Primary Power Set: Fire Blast
Secondary Power Set: Ice Manipulation
Power Pool: Fitness
Power Pool: Leaping
Power Pool: Speed
Power Pool: Medicine
Ancillary Pool: Force Mastery
Hero Profile:
Level 1: Fire Blast -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(3), Thundr-Dmg/Rchg(3), Thundr-Acc/Dmg/Rchg(5), Thundr-Acc/Dmg/EndRdx(5), Thundr-Dmg/EndRdx/Rchg(7)
Level 1: Chilblain -- Thundr-Dmg/EndRdx/Rchg(A), Thundr-Dmg/EndRdx(17), Thundr-Acc/Dmg/Rchg(25), Thundr-Acc/Dmg(39), Thundr-Dmg/Rchg(39), Thundr-Acc/Dmg/EndRdx(40)
Level 2: Flares -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(7), Thundr-Dmg/Rchg(9), Thundr-Acc/Dmg/Rchg(9), Thundr-Acc/Dmg/EndRdx(11), Thundr-Dmg/EndRdx/Rchg(11)
Level 4: Fire Ball -- Posi-Acc/Dmg(A), Posi-Dmg/EndRdx(19), Posi-Dmg/Rchg(29), Posi-Dmg/Rng(31), Posi-Acc/Dmg/EndRdx(31)
Level 6: Hurdle -- Jump-I(A)
Level 8: Fire Breath -- Posi-Acc/Dmg(A), Posi-Dmg/EndRdx(13), Posi-Dmg/Rchg(13), Posi-Dmg/Rng(15), Posi-Acc/Dmg/EndRdx(15)
Level 10: Combat Jumping -- LkGmblr-Rchg+(A), Zephyr-Travel(19), Zephyr-ResKB(21)
Level 12: Aim -- GSFC-ToHit(A), GSFC-ToHit/Rchg(17), GSFC-ToHit/Rchg/EndRdx(29), GSFC-Rchg/EndRdx(36), GSFC-ToHit/EndRdx(37), GSFC-Build%(37)
Level 14: Health -- Mrcl-Rcvry+(A)
Level 16: Build Up -- RechRdx-I(A), RechRdx-I(27)
Level 18: Blaze -- Thundr-Acc/Dmg(A), Thundr-Dmg/EndRdx(33), Thundr-Dmg/Rchg(33), Thundr-Acc/Dmg/Rchg(33), Thundr-Acc/Dmg/EndRdx(34), Thundr-Dmg/EndRdx/Rchg(34)
Level 20: Stamina -- P'Shift-EndMod(A), P'Shift-End%(21), Efficacy-EndMod(23), Efficacy-EndMod/EndRdx(23)
Level 22: Ice Patch -- RechRdx-I(A)
Level 24: Super Jump -- Zephyr-Travel(A), Zephyr-Travel/EndRdx(25)
Level 26: Rain of Fire -- Posi-Acc/Dmg(A), Posi-Dam%(27), Posi-Dmg/EndRdx(37), Posi-Acc/Dmg/EndRdx(39), Posi-Dmg/Rchg(40)
Level 28: Shiver -- TmpRdns-Acc/Slow(A), TmpRdns-Dmg/Slow(34), TmpRdns-Acc/EndRdx(36), TmpRdns-Rng/Slow(43), TmpRdns-EndRdx/Rchg/Slow(43), TmpRdns-Acc/Dmg/Slow(45)
Level 30: Hasten -- RechRdx-I(A), RechRdx-I(31), RechRdx-I(36)
Level 32: Stimulant -- EndRdx-I(A)
Level 35: Aid Self -- Numna-Heal/EndRdx(A), Numna-EndRdx/Rchg(46), Numna-Heal/Rchg(46), Numna-Heal/EndRdx/Rchg(48), Numna-Heal(48), Numna-Regen/Rcvry+(48)
Level 38: Ice Sword -- Mako-Acc/Dmg(A), Mako-Dmg/EndRdx(40), Mako-Dmg/Rchg(42), Mako-Acc/EndRdx/Rchg(42), Mako-Acc/Dmg/EndRdx/Rchg(42), Mako-Dam%(43)
Level 41: Personal Force Field -- LkGmblr-Rchg+(A)
Level 44: Temp Invulnerability -- S'fstPrt-ResDam/EndRdx(A), S'fstPrt-ResDam/Def+(45), Aegis-ResDam(45), Aegis-Psi/Status(46)
Level 47: Force of Nature -- RechRdx-I(A), RechRdx-I(50), ResDam-I(50), ResDam-I(50)
Level 49: Acrobatics -- EndRdx-I(A)
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Level 1: Brawl -- Dmg-I(A)
Level 1: Sprint -- Clrty-Stlth(A)
Level 2: Rest -- RechRdx-I(A)
Level 1: Defiance
Level 6: Ninja Run
Code:
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Well since I'm not so good at making builds yet, I have decided to ask to see if anyone has any fire/ice builds made for the secondary ice, at keeping the player alive.
I don't know if fire/ice blasters were changed with issue 18 or not, so i might as well ask about that as well.
I was told ice patch is the main secondary skill that keeps you alive.
also i welcome strategic conversation here.