Good with a ranged dps. You protect him/her with your abilities, slow the enemy or toss them away from your partner. Later game deal a lot of dmg with frenzy.
I was in trouble with the summoner spells, but the ignite is good for a killing blow, and the flash to get in or get away from a fight (as a last survivor:)), but the teleport would be a good pick too, to be wherever fast. I think the heal is useless at later fight when you have 5000+ hp.
Read the notes for more information.

Note: Your max hp:
1988 base on lvl 18
1000*3 from warmog armor
400 from Runic Bulwark
138 from masteries
summ:5526
5526*13%(from runes and masteries)=6244,38

Frenzy dmg:
260+6244,38*0,15=1196,657 plus the missing health of the enemy.