Templar Detonator review [ambush]

Skill Tree:

http://www.pathofexile.com/passive-skill-tree/AAAAAgUAAnEEBwSzBVsIZw0CEmkUTRUgFm8XHBcvGDwY2xmFGmwfAiSqKPoppSpNKo0s6S0fMZ41kjbFNtg26TrhPAU9Xz8nQYdFnUbXSVFKfUrIS0lMs04qUlNSr1XGVdZbr13GZOdnoG0ZbqpxeXTxdoJ6qoCkgh6Cx4M4hTKHdohCiPGLjI9GkzqXhZeVl_Sa4J2un9-iAKZXpwinXK1KtNG1BLXytz64k70nwBnBxcHzyAzNJs9l0NDYJNrd2wvdDeFz42rkIuvu7BjsVe0g73zyRfPd-ej60vzF_go=

Primary Items & Gems:



Secondary Items & Gems for lvling/mf:



Base Stats:
309 int
139 str
160 dex

Defence:
4882 armor (32% physical reduction)
5% chance to evade

85% fire res (141)
81% cold res (84)
81% lightning res (144)
-35% chaos res (-35)

19% chance to block spells
18% block and stun recovery increase

Misc:
60% aoe increase
20% iiq
80% iir (166% with wep switch)

124.3 life regen/s
280.7 mana regen/s
run speed increase 5%

I've been running lvl 78 maps and I can pretty much handle everything. The only thing I opt out of is a combination of ele reflect/-resistances because I blow myself up and temporal chains because it's too slow and annoying. I also tend to avoid fracture unless I'm in tight maps because it's also a nuisance.

Running level 18 artic armor atm and I think I'll be able to run lvl 20 but if I was running higher then that how would I go about doing that/would I be able to support it? (empower?)

Upgrades are fairly hard to find for cheap at the moment but I have some idea of potential improvements. Also looking to potentially work more mf into my build.

The main critique I need is on my skill tree - is there anyway I can optimize it? For example I have a +30 dex node but I need that to maintain reqs for my helm.

Or if I was to remove the reduced mana reservation nodes+sovereignty (on the far left) and move down towards the body and soul would that be more effective? - mainly in terms of maintaining a high mana/s.

Also are those 3 20% mana regen nodes the most cost efficient?

Should I remove path of the warrior and those attached hp nodes and respec perhaps towards arcane focus/life mana node/mana regen nodes that are below deep wisdom which I currently have?

Basically any tips on optimizing would be appreciated.