My PVM samurai girl uses violet courage (female version of the heart of lion, it has slightly different resists, but other stats are the same. bonus - doesn't make her look fat...).
LMC and MR I can get on most armour pieces, including runic armour. BUT DCI is only available on a few arties and jewels. My setup:
Violet Courage +15
Fey Leggings + 20
Quiver of Infinity +5
Twinkling Radiant Scimitar +6
Total = 46 (DCI cap is 45)
Both jewel slots are now free for customization however you wish - eg +HCI/+damage/+dex/+LRC/+LMC or even +DCI if you want to overcap.
Other considerations:
1) I prefer to get hit less compared to having more usable mana
2) I can leech mana back from my weapon
3) Killing an honoured mob gives you back hp/mana/stam based on the damage you have dealt to the mob. Tip: After I die, I will honour a couple of weak mobs and kill them to regain my hp/mana.
4) My warrior doesn't use alot of mana, main weapon move is lightning strike, which costs only 5 mana. The only special I ever chain is whirlwind when I am swarmed. However, this seems to trigger my weapon's mana leech more often (probably because there are multiple opponents), so I seldom run out of mana even when I get the double mana penalty for chaining.
5) The most mana intensive spells I use are Vampire/wraith form, EoO and Evasion. Neither of these requires/can be chained. Form changing spells lasts till death. EoO lasts several minutes. Evasion lasts much shorter, but can't be chained back to back anymore.
6) Only time I run out of mana is when I get mana drained/vamped. MR is potentially more helpful than LMC in this situation.