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tier II
damage doesnt increase, just gives a tp bonus that makes it faster to cap; geocrush has an additonal stun effect which helps and the merit bps are all ranged like diabolos's so it helps, I just went with what I thought looked best only thing was that i got one from the light side and one from the dark side. Heavenly Strike and Meteor Strike do nice numbers on zeni monsters, the more tp the better obviously I've used them on Iriz and Dea to great effect. Good for armed gears when the element is applicable as well but after the first gear falls off I try to switch to physical as damage should be slightly better atm.
I'd get geocrush just for a free stun but it's not imperative to me since I'm not a job thats relied on for stun, just a nice perk.
Hope that helps some
I'm more prone to do Heavenly Strike to full that the other. I have Chaotic Strike for stun and its a bit more potent that Geocrush's stun effect. Also, the TP bonus that the help messages states in the merits does increase the damage output from the Tier II blood pacts, you can test that from using Shiva's Heavenly Strike once, then let her melee, use Rush, use <pettp> to check her TP, then use Heavenly Strike again. You'll see the change in damage. I sometimes use Rush first cause it doesn't use up any TP and she gets a TP return if I"m not mistaken.
Also I found this in wiki:
Additional Notes: Additional merit points spent increase Heavenly Strike TP bonus by 40.
* This attack ignores and strips any Copy Images on the target.
* TP bonus was increased to 0 > 40 > 80 > 120 > 160% in the June 6, 2007 version update and corrected back to 40% from 60% (per upgrade) in the April 2009 update.
* As with other magic Blood Pact: Rage attacks, TP does increase damage. (Linearly, with no TP tiers)
* Formula is (floor[512+1.72*(TP+1)] + floor[(Avatar's INT - Monster's INT) * 1.5]) * MAB(of avatar)/MDB(of monster) * Day/Weather
* Shiva has MAB IV trait at Lv75 and 82 INT.