RoE builds up temporary mana regen. The others spirit spells aren't meant for spamming and RoE is kind of useless, more or less, for them.
If you hold down SB, eventually your mana per second in your character sheet gets up over 140/s, depending on your attack speed. This temporary mana per second can be used to cast bears.
Vision Quest stacks with that, so it's possible to run RoE, VQ, and PtV, for instance.
WoS and Bears compliment each other really well. WoS covers bears' weaknesses and vise versa.
I normally use the zuni set with a visage for as much mana regen as I can get without a knife. I use RoE, Blood Ritual, and whatever (except PtV). I use WoS, Bears, and Acid Rain.
I happen to use +25% SB damage between zuni String of Skulls and SoJ, which works out to +100% damage for each WoS attack (you get four times the +SB damage with WoS). At 525% damage it's more than two bears (236*2 = 472). Since I use pets, most enemies stay relatively still, so I normally target one elite at a time unless, mixing in bears when possible to hit multiple targets.
For -bears cost, these are possible:
String of Skulls with crit and -bears.
SoJ with -bears. (probably best in slot for almost all situations)
Skull Graps with -bears. (with my gear, it's either skull graps or SoJ, because I need the zuni pox, and SoJ is way better)
Mara's amulet with -bears.