If I were making an Inv/Axe tanker, I would build this way:
Hero Plan by Mids' Hero Designer 1.401
http://www.cohplanner.com/
[u]Click this DataLink to open the build![u]
Level 50 Magic Tanker
Primary Power Set: Invulnerability
Secondary Power Set: Battle Axe
Power Pool: Fitness
Power Pool: Flight
Power Pool: Fighting
Hero Profile:
Level 1: Temp Invulnerability -- S'fstPrt-ResDam/Def+(A), S'fstPrt-ResDam/EndRdx(3), TtmC'tng-ResDam/EndRdx(3), TtmC'tng-ResDam(5), TtmC'tng-ResDam/EndRdx/Rchg(48)
Level 1: Beheader -- C'ngImp-Acc/Dmg(A), C'ngImp-Acc/Dmg/Rchg(5), C'ngImp-Acc/Dmg/EndRdx(15), C'ngImp-Dmg/EndRdx(43), C'ngImp-Dmg/EndRdx/Rchg(43)
Level 2: Dull Pain -- Dct'dW-Heal/EndRdx(A), Dct'dW-EndRdx/Rchg(7), Dct'dW-Heal/Rchg(7), Dct'dW-Rchg(43), Dct'dW-Heal/EndRdx/Rchg(46)
Level 4: Gash -- C'ngImp-Acc/Dmg(A), C'ngImp-Acc/Dmg/Rchg(13), C'ngImp-Acc/Dmg/EndRdx(15), C'ngImp-Dmg/EndRdx(33), C'ngImp-Dmg/Rchg(40)
Level 6: Swift -- Run-I(A)
Level 8: Unyielding -- RctvArm-ResDam/EndRdx(A), RctvArm-ResDam/Rchg(9), RctvArm-EndRdx/Rchg(9), RctvArm-ResDam(13), RctvArm-ResDam/EndRdx/Rchg(48)
Level 10: Air Superiority -- C'ngImp-Acc/Dmg(A), C'ngImp-Dmg/EndRdx(11), C'ngImp-Acc/Dmg/Rchg(11), C'ngImp-Acc/Dmg/EndRdx(46), C'ngImp-Dmg/Rchg(46)
Level 12: Taunt -- Mocking-Taunt/Rchg(A), Mocking-Taunt/Rng(37)
Level 14: Fly -- Flight-I(A)
Level 16: Health -- Numna-Heal(A), Numna-Regen/Rcvry+(17), Numna-Heal/Rchg(17), Mrcl-Rcvry+(34), Mrcl-Heal(34)
Level 18: Invincibility -- GftotA-Def/EndRdx(A), GftotA-Def(19), GftotA-Def/Rchg(19), GSFC-ToHit/Rchg/EndRdx(33), GSFC-Build%(50), GSFC-ToHit/EndRdx(50)
Level 20: Stamina -- P'Shift-EndMod(A), P'Shift-EndMod/Rchg(21), P'Shift-EndMod/Acc(21), P'Shift-End%(34)
Level 22: Swoop -- C'ngImp-Acc/Dmg(A), C'ngImp-Acc/Dmg/Rchg(23), C'ngImp-Acc/Dmg/EndRdx(23), C'ngImp-Dmg/EndRdx(31), C'ngImp-Dmg/EndRdx/Rchg(31)
Level 24: Build Up -- AdjTgt-Rchg(A), AdjTgt-ToHit/Rchg(25), AdjTgt-EndRdx/Rchg(25)
Level 26: Tough Hide -- GftotA-Def(A), GftotA-Def/EndRdx(27), GftotA-Def/Rchg(27)
Level 28: Whirling Axe -- Sciroc-Acc/Dmg(A), Sciroc-Acc/Rchg(29), Sciroc-Acc/Dmg/EndRdx(29)
Level 30: Boxing -- Stpfy-Acc/Rchg(A), Stpfy-Acc/EndRdx(31)
Level 32: Resist Energies -- ImpArm-ResDam(A), ImpArm-ResDam/EndRdx(33)
Level 35: Cleave -- Oblit-Dmg(A), Oblit-Acc/Rchg(36), Oblit-Dmg/Rchg(36), Oblit-Acc/Dmg/Rchg(36), Sciroc-Acc/Dmg(37), Sciroc-Acc/Dmg/EndRdx(37)
Level 38: Pendulum -- Oblit-Dmg(A), Oblit-Acc/Rchg(39), Oblit-Dmg/Rchg(39), Oblit-Acc/Dmg/Rchg(39), Sciroc-Acc/Dmg(40), Sciroc-Acc/Rchg(40)
Level 41: Tough -- RctvArm-EndRdx(A), RctvArm-ResDam/EndRdx(42), RctvArm-ResDam/EndRdx/Rchg(42), RctvArm-ResDam(42)
Level 44: Weave -- GftotA-Def/EndRdx(A), GftotA-Def/EndRdx/Rchg(45), GftotA-Def(45), GftotA-EndRdx/Rchg(45)
Level 47: Resist Elements -- ImpArm-ResDam/EndRdx(A), ImpArm-ResPsi(48)
Level 49: Resist Physical Damage -- Aegis-Psi/Status(A), Aegis-ResDam(50)
------------
Level 1: Brawl -- Empty(A)
Level 1: Sprint -- Empty(A)
Level 2: Rest -- Empty(A)
Level 1: Gauntlet
<《 New Colchis / Guides / Mission Architect 》>
"At what point do we say, 'You're mucking with our myths'?" - Harlan Ellison
Nice build but unfortunately I am working with or currently working with 5 or 6 mil influence left and the Sirocco and obliteration are a little out of my price range as salvage goes for those. My poor man's build I guess 
lol a 6 mill build?!? how pointless just run a boss farm or 2 and u will easily get 20 mill
Being limited in funds really doesn't affect much. I have 2 50 Inv/ tanks. One has IO sets and bonuses coming out of his ears. One is slotted with just common IOs, because I wanted to see if there was really a huge noticeable difference. My common IO tank has done pretty much every bit of content in the game with very little difficulty. The IO sets are fun little bonuses, but by no means necessary to having lots of fun and being very effective.
�Life's hard. It's even harder when you're stupid.� ― John Wayne
�Just think of how stupid the average person is, and then realize half of them are even stupider!� - George Carlin
Most of the enhancements in that build are not top drawer. The rest can be acquired in the fullness of time with merits, for as long as you stay interested in that tanker. The build will be quite playable even with generics or SOs swapping in for the yet to be acquired enhancements.
The thing I'd prioritize first is recovery. The Miracle, Numina's and Performance Shifter uniques would be the first things on my list to obtain with merits. In normal play, it is probably easier to get those with merits than through the market.
<《 New Colchis / Guides / Mission Architect 》>
"At what point do we say, 'You're mucking with our myths'?" - Harlan Ellison
I have read several posts and each has a great way of making a great invulnerable tank. Since I am kinda limited in funds I am patching my own within my means what do you think?
Resist damage
3 (regular enhancements)
Temp Invulnerability
3 Reactive Armor(before it went up in price)
Unyielding
5 (Titanium Coating)
Invincible and Tough Hide
5 each(serendipity before they went up in price) one enhancement.
Dull Pain
2 (Doctored Wounds)
Beheader
4 (Kinetic Crash)
Chop
5 (Focused Smite)
Gash and Swoop
4 (smashing haymakers) plus 2 enhancements.
Whirling Axe, Cleave, Pendulum
5 (Multi Strike)
Taunt
5(Mocking Beratements)
What do you think? Did I do okay or am I missing anything or improve?