Hi,
This is my cooldown-centric build for Alistar, so you can spam his abilities more in fights.
Masteries: 9/21/0 with Sorcery -> Archaic Knowledge
Runes: 3x Glyph of Focus + 3x Quintessence of Swiftness
Total cooldown reduction from masteries and runes: 5%
* means consumed later for crafting
Items vs. magic-heavy team:
1. Meki Pendant*
2. Boots of Speed*
3. Mercury's Treads
4. Fiendish Codex*
5. Nashor's Tooth
6.a. vs. armor and want physical dmg: Brutalizer
6.b. vs. armor and want ability dmg: Fiendish Codex
6.c. vs. magic resistance or other: Stinger
7. Banshee's Veil
8.a. damage: Wit's End
8.b. tanking: Malady
9.a. damage: Sheen*
9.b. tanking: Phage*
10. Trinity Force
Items vs. physical-heavy team:
1. Cloth Armor*
2. Sage's Ring*
3. Ninja Tabi
4. Glacial Shroud*
5. Frozen Heart
6.a. vs. armor and want physical dmg: Brutalizer
6.b. vs. armor and want ability dmg: Fiendish Codex
6.c. vs. magic resistance or tank: Stinger
7. Phantom Dancer
8.a. vs. tank: Madred's Bloodrazor
8.b. tanking: Thornmail
9.a. vs. tank: Zeal*
9.b. tanking: Phage*
10. Trinity Force
Total cooldown reduction after #6 (3rd completed item): 40%
Though golem buff gives you 25% cooldown reduction too, I find that many other heroes on your team could benefit more from the buff, especially the mana portion of it.
Anyway, please comment. Thanks.